I've had a couple of people reach out via PM, so will do my best to explain a bit here. If you have further questions, post them here or reach out.
Free agency has been revamped in order to encourage people to bid their max (or close to it) early, while also allowing for opportunities to still fill holes if a market is more robust than you anticipated.
In phase 1, only 12 star bids or more will be accepted. If you value a player at 50 stars, it's advisable that you bid that or close to it off the bat so that you can secure your player sooner. There is no formal end date to any phase, so you have to hold the bid for 24 hours in order to win the player. While most bids are wrapped up before we start phase 2, there may still be some bid wars going on. If you bid your max, you lessen the chance that you'll have money tied up for future phases. I cannot recommend it enough - start strong with your bids.
Future phases will all operate the same way, but with different minimum star amounts and different hold the high bid periods per phase. Please check the rule thread. Please note that you are not limited to 8-12 stars in phase 2 (and successive phases). If you get into a bid war in phase 2 and wish to exceed the 12 star minimum as indicated in phase 1, that is more than okay.