It's been a long while since I first opened my adsense account; but I don't think G has set a minimum on the amount of visitors you should have before placing Adsense on your sites.

You will not get banned based on "visits", unless the traffic you are receiving are from say fake bots that click your ads etc.

As long as you are receiving "legitimate" traffic, you won't get banned based on "visits"

If I recall the first point you should consider applying at 25 UV each day

There is no limit so you can put it right now, just make sure your traffic is legit.

you can put adsense on right away on a new blog. Low impressions will not get your account banned.

there is no limit of visitors per day, but only avoid fake traffic at your site

100+ visitors is enough...