It's up to you how you'll use it. Make your own settings where to start, maybe on your local board will be nice. There are a lot of posts out there waiting to get merit but don't push yourself too much to find them, it might affect your sense of appreciation when you got stressed. There is always another day.

And now for the best / worst part. Be prepared, now you declared that you're a merit source, newbies might nuke you with PMs or someone will judge your way of giving merit, just ignore them.