If you've been going for 4 years then vesting is not in the picture. At least, with a reputable VC it would not be.
The VC should end up with a minority (<49%) block of shares, in that situation your biggest worry is a minority share holders lawsuit that you settle by giving them shares, they then control the company.
Such tactics are great for movies (they do happen in real life but very rarely).
Go with a VC with a good reputation and none of this should be your worry. The smaller the company you deal with and the shorter it's been in business the bigger the risk of trickery.
Good luck!
edit: if after the investment with the money from the investors you decide to bring on board more people that you want to become share holders in the long run vesting would be normal for the new hires. If they put money on the table to buy in then those shares (the ones being paid for) would not be vesting either.