How much is too much?

So this is my first real grow and I've vegged 5 purple haze plants to about 25 inches before I put them into flowering 3 days ago. They're in 11 liter pots (the biggest the hydro store had) and growing fine... for now.

Judging from their size, do I need to transplant to bigger pots before they explode into growth these next couple weeks, or is there enough room?

Also, when can you tell if you're using too many flowering nutes, the flowering areas are already yellow?

Grow is in the signature.

if they are already yellow, thats a good sign that your over-nutin or under-nuting bro. I think 11 liter pots should be fine if you indoor