How long should she wait before she asks again?

“I’ve had a crush on this guy for years and he just broke up with his girlfriend of 2 years. The last time he was single I waited to ask him out and he was already with someone else 2 weeks after the breakup.
I messaged him this time around to see if he wanted to grab coffee, and he said he wanted to wait a little while before he’s ready to date again. How long should I wait?”