I've been on Casaval twice, but have been turned back both times. Once in December due to questionably stable snow conditions on the ridge, and another time in April because we were moving too slowly to summit, descend, pack up camp, and drive all the way back to the Bay Area in the same day. We stopped just below the Catwalk and turned back. Our April conditions were windy and overcast, but generally pretty good for climbing. From what I've seen so far, Casaval is a beautiful climb. Looking forward to getting up it next time.
To save some time on summit day, I'd recommend setting up camp on the first large mound that's at the toe of Casaval Ridge. Though perhaps a bit exposed, it makes your nighttime navigation to the start of ridge a little easier, and gets you climbing more quickly. It also has a fantastic view of the valley, and the ridge when the clouds break, and so provides a good sense of conditions on summit morning. The down-side is that after your descent (if you descend via Avalanche Gully), you'll have to climb several hundred feet to reach your camp again.
Allow yourself time to climb the route on summit day. Ideally, either return to camp and stay there one more night, or stay locally if you prefer to warm up and dry off after the long day.