If you cover them so no light gets to them for 2 days in late aug. they will start to flower early after 6 weeks covering 2 hours in the morning for a while will help them to finish.
8 weeks inside doesn't mean 8 weeks outside.
Plants will use whats there for them to use, thin soil cuts down on support and water holding as it can dry out, make sure to mulsh and if dirt is light plant support may be needed.