Yellow new growth normal?

Hey guys,
I have been working hard to get my grow shed finished while all along looking after my babies! I still have a bit of work to do and i will be sheeting the walls with white plastic tonight.
I have a question. The plants are about 4-5 weeks old and the LR2 have just started to flower so I have set the 400w to 12/12 but I have noticed that new growth on some of the plants is very yellow looking, is this normal? I have decided to repot all of them also from 6" round pots to 8" square, about twice the size. Although I have just read afterwards that this wasn't a good idea to repot at flowering stage!! Will they be alright you think? They are only at week 1-2 of flowering.

Soil ??, pH ??, temps ??, Nutes ??

Originally potted in a homemade mix of 30% farmyard manure, 50% potting compost, 10% sand, 10% topsoil.
PH is around 6.5
Nutes are Sensi grow and bloom. 2.5ml per liter.
I did the first bloom nute after 1 week of flowering.
Oh and temps are around 20 - 28 deg celcius.

I do hydro, IDK about using Sensi in soil, that's what their Iguana Juice is for.

I think you need help from a soil person.

Why change the lighting times, L2's should stay at 18/6 for best results.

Low ryders are autoflowering and there for requiring light 24/7, some people like 18/6
I don't think they would like 12/12.