From the best of my understanding; The vesting period as related to the cryptocurrency market is the time a new ICO or crypto startup takes to share & list their cryptocurrencies to their investors and on an exchange respectively.
I have had a few experiences with startups that takes a lot of time before distribution and listing, with varied results.
Wanchain and omnitude took over 6 months to distribute and list. And while wanchain had a positive ROI afterwards, Omnitude crashed hard.
The impact caries greatly as you say, as vesting period is just one of the many factors which influences the success of a project.
Telegram had a very successful project early this year, but investors are still yet to get their tokens, and it was reputed that the TGE is 70% done, whether it would affect the project going forward is yet to be known
But sticking to the roadmap as a requisite for a successful project and if the dates are in accordance then they're still on track.
