First off, don't minraise preflop like we have done here. When we are raising with 33 from the BTN three handed, a perfectly fine play, we are looking to blind steal as we don't like almost all flops. Sure, it is great when we are called and flop a set like in this example but that happens rarely and we are not giving ourselves the best chance to take down the blinds with a minraise because of the great
odds we are giving the two other players. After the SB call the BB should be calling with any two cards technically. With the stacks as they are make a 3x raise to 7200.
On the flop our action will depends on what the SB has done but in both cases we are betting. If the SB has checked then we lead out. As tempting as it may be to slowplay a set this board is terrible for it. It is very draw heavy, with a flush and straight draw on board, and therefore there are plenty of bad turns for us. Not only that but this has hit a SB callers range really quite hard as his range easily includes AQ, KQ, KJ, QJ, JT, AT, AJ and KT all of which are interested in this flop and some which have nailed it. If we bet and he folds then it is just unlucky but we were not getting value on the turn from that hand if we checked.
If the SB has bet then we raise for the exact same reason as above - he likely has a piece of the flop, especially if he is leading into the preflop raiser. In both cases we are looking to get it all-in here on the flop.