Should I ask him out?

Am

There's a guy that recently started talking to me on Facebook after a long time, and he gave me his number and told me we should grab a coffee some time. I texted him and said that coffee would be nice, but we never set the date properly. It's been about a week and a half without any conversation and maybe about 3 weeks since he mentioned coffee.

Should I bring it up again? Do I ask him out? Do I wait for him to do it?