Signs of pre-flower before switching to 12/12?

Yes they can. If a plant thats in veg starts showing pistils( they look like its flowering but not) where the bud sites are it means one of two things. The roots are bound in the pot with no more room to grow or the plant has been in veg for too long wich is very common for mother plants to do this. The plant will still continue to grow in veg except now you will start to see the plants node spacing getting shorter and it will start getting very compact and even start showing tiny trichomes on the sugar leafs. Hope this helps i have experienced this alot with multiple plants. Message me for any other questions