"Where are you coming from now?"
Translation:Unde nunc venis?
For an interesting discussion on iam vs. nunc: https://www.textkit.com/greek-latin-forum/viewtopic.php?t=10382
Sounds like iam is correct, but since nunc can only be used in the present, it makes sense to teach that as the correct word for this sentence.
Two reasons; "unde" already has the sense of "from," and "ab" is a preposition so you can't typically break it apart from the word that comes after. Your version would say "From where from now do you come?"
(Also "nunc" is an adverb and you only use prepositions ["ab"] with nouns or adjectives)