dumping trub

I am using my conical for the first time to ferment a 10 gallon batch. I also have morebeer's yeast harvester. After 3 days of fermentation, I dumped a half gallon of trub. Then I attached my yeast harvester and it immediately filled up with yeasty material. Do you guys think that I didn't dump enough trub and just harvested a bunch of early flocculating yeast? I can remove the harvester, dump more trub then put it back on. The beer is still cloudy. (I'm using british yeast)

How many generations do you intend to be using this yeast for? If just a few, it probably doesn't matter. I tend to wait longer, harvest the whole cake, and then wash it. That way I'm pulling my next generation from the full range of yeast floccing behavior. You can probably get some directional selection by using the earliest (more flocculant) or lattest (less) over repeated generations, but I think you're gonna have to brew a *lot* of beer to see major shifts...

I am planning on using it for 3 or 4 generations depending on how things go. I guess i can just harvest a little later next generation to offset this harvest? Thanks for the reply

If you're only planning on <5 generations, I don't think there's too much to worry about (other than sanitation), but I *think* you probably want to be getting near FG when you harvest yeast.
Are you sure you even want to dump trub that early?