I've never had birds crow this early! Lady Gaga was the earliest crower I've had, crowing at 3 months or so. His mix breed sons were probably around the same age when they started, but I didn't pay too much attention to their timeline. 6, 7 and 8 months for a first crow is normal around these parts
They are doing very very good! They've started flying all over the place, so it's definitely time to add small branches in the brooder for them to climb, roost, and learn to balance on