i move mine outdoors every year around mid-may and they do not go into flower. and all those indoor plants in the pics...they're now harvested and set outside with a good dose of veg ferts and most have begun regenerating. iow, it seems the plant 'knows' when it's spring and longer days are coming. i can't explaint it scientifically, but every year i've been growing indoors i've done it this way (earlier where possible) and have never seen one go into flower after vegging indoors under 18/6 or 24/0...

and it doesn't matter much when outdoor plants are planted, they'll all flower sept thru nov...

just my observation over the years...