When should I change to "warmer" lights?

At what point should the lights be changed to warmer/yellow lights for budding? currently using flouros that are "daylight" mixed with "cool white".

As pre-flowering begins to show sex ? after 12/12 is reached? after baby buds appear? any help would be great.

Thanks.

as soon as you want to flower . some people don't change a thing .
i change over to hps when it begins to show sex or when i feel it is done vegging . hope that helps.

I change from the MH to the HPS the same time I change the light cycle, I don't know if that is the " right " way to do it,but I would consider the size of the plant , if it is over 12" tall then it should be ready to go into flower, leaving it under the flos, in my opinion, will cause the plant to do more stretching , and my guess is that you want the plant to flower now , not stretch more.