Cecil,
Yes change all the bulbs out at once. Raise the ATI P.M. 8-10 inches higher than normal, and cut your photo-period by 30%. After week one drop the P.M. 4-5 inches and increase the photoperiod by 15%. Do the same on week two and you should be good to go. However I would let your corals tell you what's going on. If they start to bleach out raise the P.M. back up and cut back on the photoperiod. Enjoy you new lights! BTW what combo did you go with?