Negotiation Help

[Adam Smith]

Hey everybody, been reading the forums for a long time and decided to start posting. I know I need to work on my profile but wanted to get my question out here first.

I'm currently trying to buy a vacant lot to build a duplex on. An elderly man owns it and he previously had a duplex on it that burnt down. He told me that he doesn't want to put anything else on it because he's too old. He's had a for sale sign in the yard for about 6 months now. I've been eyeing the lot for a while now and finally in a situation where I can buy it.

Yesterday I called him and offered 4k less than what he's asking, he countered by lowering his price by $500. I countered back by raising my price $500. I'm willing to go up a little more but not much. We talked for a few minutes, he asked what my plans were, etc. the conversation ended by him saying he has my number he will call if he decides to accept my offer. My question is what should I do next? Wait on him to call or go ahead follow up with him.

Thanks for the help.