Once I had enough peppers I would start the ferment. For the habs, it was pretty much right after the harvest (really prolific plants!) For the aji, I saved the harvest by freezing the peppers. I did the ferment using both de-thawed peppers and fresh (about 50/50).

Lacto fermentation uses the naturally occurring yeast on the peppers / veggies to ferment. Lactic acid bacteria and kahm yeast do not need oxygen to survive, unlike the bad bacteria / mold. The ferment happens naturally, all you need to do is submerge the peppers in a salt water brine. The lack of oxygen and salt water prevent growth of anything nasty. Here is an easy to follow guide if you want to try