"We are now coming to the city."
Translation:Ad urbem nunc venimus.
Gaffiot and dicolatin don't have "iam" (so maybe it's rare?), but I found it here:
They give: now, already, by or even now. Besides
My level in Latin doesn't allow me to know wether it's very common, but it does exist, and should be accepted.
Found many occurrences here too (so you must be right.):