Watch the Pentatonic Picking Exercise 1 online guitar lesson by Jeff McErlain from Beginner Blues-Rock Soloing
I must admit this first exercise at 60 BPM may be a little fast for you with triplets. I highly suggest that you learn the pattern first before using the metronome. Just very casually learn the notes, get the feel of them under your fingers, pay attention to the picking, and take your time. If you don't, you'll most certainly have problems playing along with the metronome!
One of the most important pieces of information that I can pass along to you is that if you cannot sing what it is you're trying to play in your head, you cannot play it. More simply put, if you don't know what it is you're trying to play, how can you expect it to come out? I honestly forget this lesson all the time! I'll keep on messing around with a lick or pattern and get frustrated as I'm not getting it right. If I slow it down, and pay attention to the notes and get them in my head, that usually solves the problem. It seems obvious, but since we're humans, we do lots of silly things.