Welcome to AFN!
I usually transition to 2700K about the same time I'm transitioning to flowering nutes, typically when vertical growth is slowing down which I find is about 4-5 weeks after germination (strain dependent.) Although I don't think it makes much of a difference (but do it anyway), I switch over my eight CFLs over a period of 4-5 days.
You might want to stop by and say hello over in Introductions. Also, as a first time grower you might want to start a grow journal. This forum is great for first timers; so many helpful knowledgeable people ...
Selfishly, I'm interested in hearing about your grow space. If you have a small space, ten 43 watters can be a real challenge heatwise.
Welcome again and good luck with your grow!
Bayes