Hey Vince,
We started on a 5'6" Shred Stixx, but I was unable to ride that and had to size up to a 5'8". Over the course of the next - maybe 18 months we got the boat dialed in and my skills became proficient and I routinely ride a board in the 4'5" range.
I never surfed before wakesurfing (and I have to have someone call out the wave is approaching now - my eyesight is so bad
), but did skateboard as a kid and we've been snowboarding for - shoot 8 or so years. We also wakeboarded for a good 4 or so years before starting to wakesurf.