While you wait for Roger to jump in, here is my take on your dilemma. You won't plane any earlier unless you are willing to pump. My estimate is that vigorous pumping will let you plane two knots earlier. Mild pumping, one knot.
Frankly, planing on your kit without pumping in 10 knots (white caps beginning to form) is pretty good. With a formula board and an 11.0 race sail at 168 lbs, I can plane without pumping at about 10 knots.
Normally, I pump up on plane, then maybe pump two or three times more to gain speed, hook in, get into the front strap, then the back strap, then sheet in. The quicker I can get weight on the back foot and pressure on the fin, the quicker I can accelerate even more (keeping the board flat and not sinking the windward rail).
If you lose speed while getting into the foot straps, you may have not had enough speed to begin with.
If I sail with my 11.0 in winds from 4-12 knots with an occasional gust to 15, I estimate that I will easily double my planing time with pumping compared to not pumping. The 4-12 knots would be a typical summer 10-15 mph wind forecast in my area.
I like the extra upper body workout that pumping provides (not fun, but good for my fitness), so I am willing to do what is necessary to get planing. The down side is pumping your brains out 6-8 times and still can't get on plane. This always causes a few foul words to pop out of my mouth. This doesn't happen too often since I can "read the water" pretty well. This usually happens when I pump in a gust and immediately hit a hole.
Hope this helps a bit.
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.