Buy now, don't wait for him, if you can do it now go for it, if he refuses to buy it with you maybe you need to sit down with him and find out why. Maybe you could buy and if he wants to live with you he pays you rent (don't let him get away rent free) its important you do what you want, if he won't commit don't let it stop you doing it. Now is a good time to start looking around, I'd recommend siging up to rightmove.com
Good luck, be positive and follow your dream, have no regrets