Had a lot of years going up in the spring before I moved there and funny thing was the ice around Anchorage [Lake Hood] used to go out about the 1st week of May or pretty similar to when the lakes cleared here, but the birch trees were always leaved out further in Anchorage, because of the days being so much longer at that time of year I suppose?
It is always very interesting how fast things start to green up, gotta be the long days. Of course fall comes on just as quick. Just at the prep stage now, big push to get everything we can into a container and shipped by the first of May. June through August no days off, but always good people.
Guessing you're going to be on the road system out of AKN then. You'll be on silvers primarily, maybe second run of reds(sockeye) on the Kenai. You should think about a day targeting rainbows as well, could be a lot of fun. Of course fishing for Butts is always good.
Either way it will be a great trip. One piece of advice I would offer, if your brother asks you to come up with an extra 300.00 bucks for a fly out. Do it. You won't be sorry.