Neat project you have there. You have a unique situation where others can (and will) introduce fish that will affect the pond. You also have a lot of minnows of unknown origin. Given these facts, I would stock in the most cost effective manner available since a lot of factors are out of your control. Stocking adult bass before bluegill is not the norm, but if you are getting a good deal on them I say go for it. Also remember that once these bass are in, everything else you stock must be large enough to survive predation. Your bluegills for example should be 5". This is not a big deal if you can catch your own in this size range. If you have to buy them, they are much more costly than the smaller sizes.
Now lets talk about numbers. 300 lbs of bass sounds like overkill to me, especially with just a minnow forage base and unknown fertility. When you say minnow I envision 1-2" fish. Your LMB will eat these but they are not preferred and growth will be slow. you may need to supplement this food source until the BG get established. For 4 acres, you should stock a minimum of 200 adult BG. I would not hesitate to stock as many as 400+. Good Luck, keep us updated.
