וְהָיָ֗ה כִּ֤י יְבִֽיאֲךָ֙ יְהוָ֣ה אֱלֹהֶ֔יךָ אֶל־הָאָ֕רֶץ אֲשֶׁר־אַתָּ֥ה בָא־שָׁ֖מָּה לְרִשְׁתָּ֑הּ וְנָתַתָּ֤ה אֶת־הַבְּרָכָה֙ עַל־הַ֣ר גְּרִזִ֔ים וְאֶת־הַקְּלָלָ֖ה עַל־הַ֥ר עֵיבָֽל׃
And it shall come to pass, when the LORD thy God shall bring thee into the land whither thou goest to possess it, that thou shalt set the blessing upon mount Gerizim, and the curse upon mount Ebal.
Sifrei Devarim
(Devarim 11:29) "And it shall be, when the L-rd your G-d brings you": "And it shall be" connotes immediacy. "when He brings you": Take upon yourself the mitzvah stated herein, in reward for which you will come and inherit.