Money wise you are sorted. I don’t ever bet, so at start of game I don’t get that kind of money until I get a champ. What’s your trainer like? If he’s poor then maybe upgrade him.
I would concentrate on getting fights fired off now. Try get your boxers some belts. Once you get a champ you make money fast and then start upgrading gym.
I only sign amateurs who have a few greens, ring generalship and resistance are main things. I go through and look at them at start of every year.
I would just concentrate on the gym you have. Upgrading it a bit would be ok. Don’t go crazy and blow all your money though. Running costs of gym go up when you start upgrading and expanding.