Switch to flowering?

Hi, it's my first grow and I've been vegging my 5 plants under a 600w dual spectrum bulb for about a month now.

They are White widows and around 15cm high.

I'm in a growtent which is 2m, and the pots are 30cm tall, so I want to know how much more height the plants will gain in the flowering stage. I don't want to flower too early or too late, and either worry about not having enough room, or not utilising all my space.

With the light at the top of the tent it takes up about 50cm of space, and then obviously I need space between the light and plants as well.

Is there any rough guide for how much more (%wise or otherwise) my girls will grow once I go to flowering?

Grow diary + pics - https://www.rollitup.org/grow-journals/214881-first-grow-growroom-white-widow.html
most recent pics are still about a week old :S Lent my camera to a friend for a wedding , will try and get some phone pics this evening.
Thanks in advance

Most plant's will double in size during flowering,white widow can get big
bud they will roughly double in size ,so including your pot height they
may be 1.5m or over so you should be just about fine

Thanks that's great, I'll switch over to 12/12 this evening then