It can come out in pieces or the whole thing. It looks like a glob of snot. It can have a little blood in it. Also, if it comes out in pieces, it can regenerate. I'm not sure of the appropriate time for it to come out.
Yes it can come out as early as 28-30 weeks n usually doesn't come out all at once it does not regenerate however it never comes out all the way until labor n delivery so there's always more that's gonna come out n yea it's really gross looking it definitely looks like a big glob of snot and usually the part with bloody show in it doesn't come out until at least 32-34 weeks