Security deposit for prospective tenant question

[Martin Kimmel]

Please help! I verbally offered my place to a prospective tenant under then understanding that security deposit is due at time of lease signing. We were planning to meet today to sign but now he's asking if I wait to a few days to cash his check.  He later said he could make it work if necessary but would really appreciate a few days to get the money together. 

This makes me want to pull out because he can't come up with the deposit. This is a sign he's going to struggle to come up with rent every month. Can I, or should I pull out? What would you do? Are there any potential legal issues I need to worry about? Nobody has signed anything but he did technically agree to my verbal terms because he ultimately said he could "make the deposit today work if necessary". 

thanks in advance for your advice!