goals for the pond will determine when to stock predators.
I had to stock out of season as you. Similar sized pond, stocked with 600 bluegill and redear in March. I began to see BG beds in June.(in the southeast though) I stocked LMB in Aug. and HSB in Sept.
I didnt want the BG to get too far ahead of the bass so as they could not be conrolled, BUT, I was aiming more toward a better BG environment, and the bass as the controlling media.
If you want giant bass as many people do, then wait til fall for bass, or, even late next spring. Just remember that 3/4 acre will support only a small number of large bass.