That's not a bad plan ilikecandy. It's definitely the best plan for the majority of people learning to surf as an adult.
Usually if someone between 18+ learns on a long board then they tend to stay on the longboard/funboard shape forever, with a very few eventually downsizing to a true Shortboard shape.
I'm sure you already know this but the transition down from a 9'0" to a 6'2" is almost like learning to surf all over again. The sweet spot is smaller, the balance is different, paddling is much more difficult and even being in position on a shortboard can be challenging even though they can do it on a LB with no problem. Nevermind fighting the current on a 18 second ground swell at a beach break, most guys will just pack it in and go back to the LB at some reef break with a channel.
If you learn on a shorter board (7'0" or less) then it easier to step down to a true shortboard, once they grasp the basics.
I was determined that speed, quick turns, barrels and the like were why i was interested in surfing. It was a longer road to catching waves but the waves I caught were mind blowing. In the end I've been able to score mind blowing barrels and some thick South Pacific juice that I never would have imagined if I started on a LB. I wouldn't have transitioned over to SB'ing, it would have been to much work to learn to surf all over again.
That's just me though and 99% of the world should start on the LB and downgrade as they get better. I knew I liked adrenaline so SB'ing made sense to me, i actually used to like getting pitched over the falls on bigger days for the rush (I've since smartened up) :)