Without going too deep into this, I've found doubling every year to be easily achieved... and I'm in a colder climate. Plan to start feeding early on, build up big strong hives in 3 deeps that can be split (divided into nuc boxes) leaving the original hive at 1.5 deep (~15 frames + 5 frames of foundation). A few weeks later that original hive will be ready for an excluder and honey super. The other 15 frames are put into nucs... 2-3 frames each plus foundation, introduce a queen cell. Of course this is optimistic assuming you can get that many good frames (a suitable mix of brood and honey/pollen) to make nucs. These nucs will need to be built up for the rest of the season to get through winter.
The slower alternative is to build up a 3-deep hive, split a single box off, make a good crop off the 2-deep hive, the single box gets a 2nd once it has a laying queen... will be nice and strong by the Fall without too much work. Will be very strong if you have drawn comb.
The biggest delay in any expansion is the lack of comb. You can have all the queens you want, if there is no space for her to lay your hive is killing time!
My experience (if my memory is correct)...
year one - start 2, finish 5
year two - start 5, finish 8
year three - start 7, finish 13
year four - start 12, finish 22 (20 doubles, 2 5+5+5 nucs)
year five - start 20 (18 2-deep, 2 5+5+5 nucs), ... currently 47? (triples 3, doubles 17, single 4, 5 frame nucs 23)
I'm going for a lot more nucs this year... with the goal of selling them. First attempts at proper queen rearing this year, not just walk-away splits or purchasing mated queens. Grafts going well so far. Hives are looking fantastic, and I'm hoping the heavy splitting I did last week will knock down the swarms in July.
I make no claims of being a commercial beekeeper... I'm investing money in a potential business, which is better than buying a case of beer every week. I do all my work with a station wagon (Outback and Focus) and a trailer. I'm definitely breaking even on my endeavours, which is allowing me to purchase more equipment.