Any guesses on the age of this kitten?

https://imgur.com/a/tG4Ze1Y

This is Mo. He wandered into my work last month and just stuck around. He needs flea meds, shots, and to get fixed but I'm not sure how old he is. I'd ask the vet but it's a 2-3 week wait to get in; I don't want to finally get an appointment and then have him be too young or something.

I'm guessing 4ish months? Looks like a Holstein. Thanks for your help.