Agree, should plane almost instantly unless the boat is overloaded. Check your wear-ring clearance.
What is the engine doing? Is it going straight to redline like the "clutch is put to the floor", or does it sound/feel like it is pulling constantly and just not getting there quickly like the "clutch is slipping"?
Usually this problem is either cavitation from air getting sucked in from the engine bay, or worn ring.
I had mine loaded down, 4 full grown adults (I am 200 lbs myself), little 14' boat single 110 hp engine, and it was slow out of the hole yesterday, in my opinion, but it still only took about 5-6 seconds. Normally it is 2-3 seconds.