Martin brings up a good point: the major drawback to starting early is the possibility of pests.
These pests:
#1 fungus gnats (super common)
#2 spider mites (somewhat common)
#3 mealy bugs (pretty uncommon, depending)
#1 is combatted by using water with mosquito dunks and avoiding rich potting mixes, compost tea, or compost in your mix, but neem oil sprayed on the soil top will kill them also. #2 ... man, these bastards suck, and sometimes it's tough to figure out where they come from, but neem oil spray in multiple treatments of all of the plants nearby to the infected plants. #3 is unusual, but with light infections, a simple application of rubbing alcohol on a q-tip will help.
There are always downsides to everything. I personally try not to wait, because I think cuttings rotting in a fridge is a bigger problem than the insects.
As usual, I like Martin's ideas and philosophy. He's always rational but adventurous, it's always nice to see!