There is a "then" referring to the past, and there is a "then" referring to the future. "Then began men to call upon the name of the LORD" (Genesis 4:26); "then she said, A bridegroom of blood" (Exodus 4:26); "then sang Israel" (Numbers 21:17); "then sang Moses"; "then spoke Joshua"; "then David said" (1 Chronicles 15:2); "then Solomon said" - these refer to the past. And there is a "then" referring to the time to come: "then you shall see and be radiant" (Isaiah 60:5); "then shall your light break forth like the dawn" (Isaiah 58:8); "then shall the lame leap"; "then shall the eyes of the blind be opened" (Isaiah 58:5); "then shall the virgin rejoice" (Jeremiah 31:12); "then was our mouth filled with laughter; then they said among the nations" (Psalms 126:2) - these refer to the time to come.
The Word Then Pointing to Past and Future Redemptions
Yalkut Shimoni on Torah 241:5
יֵשׁ אָז לְשֶׁעָבַר, וְיֵשׁ אָז לֶעָתִיד, (בראשית ד, כו) "אָז הוּחַל לִקְרֹא בְּשֵׁם ה'", (שמות ד, כו) "אָז אָמְרָה חֲתַן דָּמִים", (במדבר כא, יז) "אָז יָשִׁיר יִשְׂרָאֵל", "אָז יָשִׁיר מֹשֶׁה", "אָז יְדַבֵּר יְהוֹשֻׁעַ", (דבהי"א טו, ב) "אָז אָמַר דָּוִיד", "אָז אָמַר שְׁלֹמֹה", הֲרֵי אֵלּוּ לְשֶׁעָבַר. וְיֵשׁ אָז לֶעָתִיד לָבֹא, (ישעיה ס, ה) "אָז תִּרְאִי וְנָהַרְתְּ", (שם נח, ח) "אָז יִבָּקַע כַּשַּׁחַר אוֹרֶךְ", "אָז יְדַלֵּג כָּאַיָּל", (שם, ה) "אָז תִּפָּקַחְנָה", (ירמיה לא, יב) "אָז תִּשְׂמַח בְּתוּלָה", (תהלים קכו, ב) "אָז יִמָּלֵא שְׂחוֹק פִּינוּ אָז יֹאמְרוּ בַגּוֹיִם", הֲרֵי אֵלּוּ לֶעָתִיד לָבֹא.