Trying to time things rarely works out for the best. You may save a little money but you will lose the time from riding. Based on where you live, you should buy now when you can ride. Chasing the latest and greatest will only drive you crazy. If you have a bike than you could wait for the sales but if you do not than I would recommend getting one. As was stated before, deals are usually found on the smaller or larger models that are left over, not the common sizes.
The 2016 Giants that you listed are not going to be much of a difference from the 2015 anyway. Strike now and ride while you can.
Good luck either way.