Potty training earlier than normal & split family. tips & advice!! Please!

My son is 21 months this month, he is VERY interested in the potty. Tries to sit on it when he needs to go, constantly pulls his pants down, can say potty etc. the few times I’ve sat him on the potty he just plays with his penis. My hesitations are, I nanny so we drive to work 4 days a week and to his dads 2x a week which is a longer drive. His dads also expecting a baby with his fiancé in September and I feel our son might regress or add too much onto her plate with the new baby. Has anyone potty trained this early? I would just commit to it if other factors didn’t exist. My first son I potty trained at just past 2 and it felt like a long drawn out process, and he majorly regressed when I had his brother 9 months later. If anyone has, what do you recommend??