12/12 right away.

Can I start my plants on 12/12 right away?

Yes they will flower as soon as the plant is able If I remember in about 4 weeks. I did this several years ago and it worked I just did it in a perpetual style and it was alot of work.

Sure you can. You can expect a plant thats 1-3' tall finished height if its indica dominant. Sativas will be a bit bigger, as they dont generally begin to flower until they have 3-4 nodes, and strech a bit more as well.

You wont gain much using this method as far as yeilds are concerned, but its a good way to stealthily maintain a microgarden.

Just like HighPlainsDrifer said, if you're growing a tall sativa and don't want her sticking through the roof, 12/12 from seed is a great idea and will still give you a good yeald and a plant under 1,8m.

Indicas on the other hand don't seem like worth the while and money. To invest all that electricity and time for a plant that may offer even less than 5g dry. But it's still damn good for a micro grow where the investment is small and you can plant 4-6 indicas together, since they will never ever grow over 40cm.

So...to answer your question, having all this info in mind... depends what you're growing, depends what you want to get from what you're growing and depends on the space and investment you want to put out for what you're growing.

Cheers, and good luck with the grow, bro.

Plants make most of their fiber at night (stretching) and they don't flower until they are mature (hormones) anyway. You'll end up with a lankier plant and less harvest weight, but the plant will start flowering as soon as it's ready so maybe you take a week off the end, but less harvest too, so...

I'd just veg until you see preflowers, then go to 12/12.