Are 5 gallon air pots big enough before transplant in late July early August into 30 gallon containers of stated In mid may

Its a big step up from peat pots to 5gal. I would go along the line of multiple transplants/up pots. Eg, peat pot to 1L to 1Gal to 3Gal to 5Gal to outdoors. I like to transplant into something that is 2-3 times the previous volume. This helps the root ball become nice and dense in the pot. Planting outdoors is great into earth if you have the option to do it. If not 30Gal is more then enough. Pants will need a light cycle of around 14/10 to prevent flowering from happening. This will not be possible with autoflowers you need to use photoperiod plants for an extended veg period.

I not exactly sure what size pot is best but probably bigger than smaller. I think your timing might be a little off as it is better to have your plants established before they sex and go into stretch which will start to happen outside around mid July. So I my guess final pot by July first. But I also live in a northern area so I have less time to get any plant outdoors. Hope this helps.