With another three months to grow, I should think they'll be fine.
Yes, good advice about raddling. Or they could buy two and use them together, or, if they need to keep track, each on half the girls and swap after 17 days.
I bought a Shetland tup lamb from Jaykay, originally intending to use then sell. He tupped everything he was asked to, including a full-grown NoE Mule. That last I didn't take to him until he was 8 months old, and I was still dubious that he'd be able to reach. I thought she was a-tupping again 17 days later, so moved them onto very uneven ground, thinking they'd find an appropriate height differential to use
. In fact, judging by her lambing date, he'd caught her the first time.
I said 'originally intending to use then sell', but of course Jaykay then sold her flock, so my plan of doing the same every year wasn't going to work out. So I kept him on to see what his lambs were like. They were excellent, exactly what I wanted. So I kept him and used him again. And, because we want to merge my flock and the Zwartbles where I'm going, and create a flock with good fleece and a more manageable size than the pure Zwarties, he's had another stay of execution and is going to Cornwall with me, to tup the Zwarty ladies there, and the unrelated girls I take with me. His own daughters (those I take with me) will get another year to grow. Fingers crossed the fencing works...