when the plants mattured then you can start the flowering (12/12) normaly after 6-8 weeks
so if you allready see signs of first stage flowering, no prob and you could wait asswell to get em big and bushy
just keep on the 18/6 and keep giving them the grow nuetrience untill you think they are big enough then switch to 12/12 and change top flower nuetrience.


info 18/6 light reprecents early summer light cyckles
long houers for seedling and grow
when held at this stage the plant will think that its still early summer
and will hopefully not start to flower untill you set the lights on 12/12

and the 12/12 light reprecents of course late summer light cyckles
short houers for flower and stronger root as the roots grow best when its dark...i had to wait a cupple of weeks myself
couse i had 23 plants stuffed in the same space but 10 of them grew 18 days slower then the others couse i had to replant them as they never got from seed to plants but now they all are set to flower same time some a bit bigger
so it should be allright to wait.
a good grow to you