The placement you laid out looks good but without knowing the size of the pot, it’s hard to tell what size bit. Maybe a 1/2”-3/4” bit? And mayyybe adding another 2 holes.
One thing I would recommend though is to use a small bit to start your hole, then move up to the bigger bit. Don’t put too much pressure on the drill so you don’t crack the plastic. Let the drill and bit do the work.