What is the word for "ago" as in: "a long time ago", "three years ago"?

ago → pase, desa
some time ago → kèk tan pase
three years ago → twazan pase
many years ago → anpil ane pase
a long time ago → lontan, nan tan lontan 

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words