I don't think it's bad to meet someone you just met online. I met a guy online, we chatted online for about a month then I gave him my #. Then we talked for a few weeks (maybe 2-3) then met out in public. He was not who he claimed to be. He said he was single - he was not, he was legally separated. He looked absolutely nothing like his profile pics, not even close.
I actually started getting feelings for this guy (and I am tough), but after feeling deceited I just couldn't do it. Regardless of how soon or later we met, didn't matter.
If she met him at a grocery store and he invited her to dinner or a date the next night would be fine also. So long as they are in public.
Now if he is trying to meet at his/her house immediately is an issue. Big issue!!!! Big NO-NO!!!! :)