Please adivse re my Cistus cuttings

I have for the first time successfully taken cuttings! 

My cistus cuttings are a few inches tall, but are starting to grow straight up, on a central stem, without any bush like habit. 

should i let them do their thing, or should i lop off the top to see if it will become bushy?

also how big should they be before i put them in the ground? The tallest is about 7'' but has no real structure to it. 

thanks