I usually recommend using Tetra SafeStart for live bacteria seeding. It is a proven product with the right species of bacteria for aquarium nitrogen cycle. A lot of other products out there don't have the right species of bacteria and sometimes they drown in the water after a few weeks and thus crash the seemly finished cycle.
Tetra Safestart usually gives you near "instant cycle". I have used it on multiple occasions. In one case, it cycled the fish tank within a day. In another case, it only took a few days to get ammonia and nitrite down to 0ppm.
Anyway, your cycle is incomplete at the moment. Unless you want to sacrifice the new fish, I won't add them now.
The usual fishless cycling can take anywhere from a few days (with the help of Tetra Safestart), to as long as more than a month if without any heavy seeding.
