When and How to harvest romaine??

I had the plant growing for some time, it's probably 6 or so weeks in but 2 of those my res temps were WAY too hot so no growth happened and the roots went to hell. I got things in control and for about a week now they have been taking off. White roots in a mass amount.

Can someone post a photo or something for me to compare and gauge when I should be harvesting my crop? Also, how do you manage the harvesting? Is it a simple clip at the stalk or something i'm not sure about at all?

Don't have any pictures. I clip the outer leaves all of the time. It will keep growing until it gets to cold. You find the leaves tender and tasty, I would rather harvest early rather than late since the leaves can get tuff with age. The best way to tell is taste it.

I'll take a picture or two in a little bit, I figured they would be needed.

Here are some pics of my plant. Do I just clip close to the stalk, or further up the leaves? Is it even ready?

Anyone have any tips?

clip the leafs here and there don't harvest to much at once.

So I just took 1 large leaf, and 1 small leaf. Old/Young. Both are really bitter.

I can only attribute this to water temps. That being said, I got them down to a (measly) 74-75*. I know it's not ideal, but it's a good bit lower than before.

What causes bitterness?