If there is a slight bowl wobble, it's not good.
If it took him three tries, he may have trouble either with the floor, the base, or the wax horn.
I first drop the toilet on the flange without wax, to see how the floor lays.
this will tell me if shimming is needed.
If I shim, I do it from the back, pinning the front of the bowl down.
Then I can pull the toilet back up, and drop the wax on the floor.
If the wax prevents the toilet from dropping down to the floor when pushed, then it may be that a horn is being used and preventing the two meeting.
Caulk around the base helps to stick it to the floor too.