You might have to do it again...and again... but that is cycling. It needs doing until there is enough filter bacteria are able to break down the ammonia and convert it to nitrite, and then different bacteria to convert nitrite into nitrate.
If you had a test kit (I know you're getting one) and were doing a fishless cycle you would add an artificial source of ammonia (ordinary household stuff) and then test for each thing daily, ideally same time each day, before changing water. You'd see how the ammonia levels peaked, then started to drop while nitrite levels climbed higher, then these started to drop and the less harmful nitrate levels climbed. Once you were getting a steady result of 0 ammonia, 0 nitrite, and a constant level of nitrite around 10-20 (it does vary), that's the cycle finished.
Because you have fish, you can't afford to just watch the ammonia peak, then the nitrite, and finally the nitrate. You have to manually do what the filter is for now unable to do, ie remove the ammonia. Unfortunately it just takes as long as it takes - frustrating, but necessary.
You will get plenty more babies, don't worry about saving them!