It's a pretty great time to exit if you're ever going to. The stock market is going gangbusters, most valuations are on the ceiling. If they can't fetch top dollar for their business in this environment, they never will. It would suck to wait 18 months because you tried to time it higher, have the market sink into a bear, and then be stuck with either staying private for many years waiting for the next wave, or pushing an IPO in a very poor environment.