Quoting Commentary for I Kings 8:2

the month of Spring is so called because it was during the Springtime that they left Egypt. The Dissenters have claimed that one may not perform the Paschal sacrifice until Spring-time. I have replied to their nonsense elsewhere [comment on Exodus 12: 2] (nevertheless, we must acknowledge that the court did examine whether or not Spring had arrived). Know that in the Hebrew language the months have no proper names. The names that appear in Scripture — like Nisan [Esther 3: 7], Sivan [Esther 8: 9], Kislev [Nehemiah 1: 1], Ṭevet [Esther 2: 16], and Adar [Esther 3: 7] — are all Aramaic. Consequently, Scripture had to tell us, “…this being the month of Nisan” [Esther 3: 7]. The only Hebrew terms that we find are the descriptive terms “Splendor” [I Kings 6: 1], “Mighty” [I Kings 8: 2], and “Wilt” [I Kings 6: 38]. The original rule was that the first month (the month from which the others are counted) was to be reckoned with the coming of the Spring — whether the previous year had twelve or thirteen months being of no concern. However, our ancestors, of blessed memory, added other considerations, in addition to the Spring [Sanhedrin 11b]; and all of their words are true.

ויקהל העם, “the people assembled;” whenever the expression ויקהל appears and is followed by the word: על, it means: “against,” i.e. it is the Torah’s way of condemning such an assembly. On the other hand, if the word following the word ויקהל, either in the singular or the plural mode is followed by the word אל, this signifies a positive development. Compare Kings I 8,2 where the people assembled around King Solomon to watch the Holy Ark being transported to the newly erected Temple. ויאמרו אליו קום עשה לנו אלוהים, “they said to him (Aaron) arise and make a visual image of G-d!” According to the plain meaning of the text there can be no question that Aaron had no intention to allow the people to revert to idolatry, G-d forbid, or somehow to replace Hashem or His prophet. Moses, while on earth, had frequently been referred to as elohim, either when compared to the creature issuing commands in the name of Hashem to Pharaoh, or as communicating G-d’s law to the people. If Aaron had intended to make an idol, Moses would have had to execute him as a false prophet! Not only that, but how could that “false” prophet subsequently have been appointed as the foremost instrument of securing Israel’s atonement?! Moreover, how could he have become the first priest and all his male offspring became the priests of the whole people? Not only that; We did not find that the Torah charged Aaron with any sin until the events at מי מריבה where Aaron did not stop Moses from striking the rock to produce water. There is not a single sage that ever suggested that G-d would appoint as a prophet someone who would eventually revert to idolatry. There can therefore be no question that what the people demanded of Aaron was not a return to idolatry. The problem had been that Moses had not announced by what date he would return from the Mountain. The reason that he did not do so was simply that he himself had not known when he would return. G-d had told him that He would give him the Tablets, but had not said when. When the people noticed that Moses took an inordinately long time, far longer than a normal person can go without food or drink, they worried that he might have died, in fact they were convinced that he had. They therefore requested from Aaron that he make for them a replacement whose function would be similar to what had been Moses’ function vis a vis Pharaoh, i.e. elohim. The Torah even spelled out what the assembled people had in mind, i.e. כי זה משה האיש אשר העלנו מארץ מצרים לא ידענו מה היה לו, “for this man Moses, who took us out of Egypt, we do not know what has happened to him.” In other words: they wanted to replace the Moses the man, not the deity, or semideity. When David in Psalms 106,20 is quoted as having referred to that episode with the words: וימירו את כבודם בתבנית שור אוכל עשב, “they traded their glory for the image of a bull that feeds on grass,” the people had referred to Moses, not to G-d. G-d had performed so many miracles which had been orchestrated by Moses, that they had been quite prepared to prostrate themselves before such a leader. An alternate interpretation: the people asked for a creature that Hashem would use to imbue with His glory, [similar to how He spoke from between the cherubs on the lid of the Holy Ark, the cherubs and their faces of innocent children not being so much different from the golden calf, the principal difference being that no one ever got to see them. Ed.]

ראשון הוא לכם, “it is a first for you;” from now on this will be a first month for you, the reason being that you will start counting by months as a reminder of when you received your freedom from slavery. It will forever remind you of the Good that I have done for you. Up until now, the month of Tishrey had been the first month and Nissan the seventh. This agrees with what is written in Kings I, 8,2: בירח האיתנים בחג, “in the month of the original ones “ (the patriarchs, or in the months whom the early generations of mankind referred to) as the seventh month.”Yonatan ben Uzziel translates the word איתנים as “the ancient generations of man called it the first month and now it is the seventh month.”