Auto flower organic Grow HELP

I have a Critical Jack Herer Auto that I wanna grow under a 600w hps/mh that dims. I was gonna grow at 300w mh till pre flowers show then 600w hps till harvest. I have a 3 gallon fabric pot some Mexican Bat Guana, dolomite lime, worm casting, perlite, and Sunshine mix #4. How do I mix this for my auto? I want a nice organic grow for this one. This will be the only plant under my light. Also do I switch light to 12/12 once I see pre flowers or stay at 18/6?

im no pro but since no one else has replied ill take a crack at it. autoflowers use age rather than light cycle to determine flowering. so i would keep it at 18-6 or even 20-4. otherwise you are just wasting growing time.

in terms of soil id mix it according to the sticky in the organics thread or here
http://hightimes.com/grow/ddanko/3873
of course i havent completed a grow yet but I have read A LOT.

I'm going to be giving FFOF a try with some Auto Blueberry and auto Biodiesel Mass (heard great things about the strain and got six free seeds yesterday so stoked)
My hope is that there will be enough food for the first month or so.) ever consider something like that?

If you're using auto flower soil mixes are probably best avoided (I would avoid auto flowers personally)...chemical ferts are best for autos because you have such precious little grow time.

If wanna grow organic with auto flowers I would keep the mix simple. The sunshine mix with worm castings mixed into it (20% of your potting mix)

Then make steeped teas with the Mexican guano and some kelp. Use Indo guano when you're in flower.

The link below has a fool proof method for growing organic but with an auto flower you're not gonna have the time you need. Auto flowers quality aren't that great quality either...
https://www.rollitup.org/t/organic-growing-an-introductory-guide.921380/