Irene, what I've read and practiced, is that juniper cuttings (hard and semi-hard) are best taken when its cold. They have gone dormant, They the wake up in side that nice moist warm green house and go to town. This method has worked for me for a lot of years. I'm sure there are as many opinions on this as there are grains of sand on the beach. All I know is that it works for me and I get an extended growing season the first year.
As far as me commenting out of zone...I won't

...haven't tried it outside of 6 and 7 so I'd be only guessing. Try it this winter for grins and giggles and then you can tell me. If Nigel is around he might comment....swapped with some shimp cuttings for some cork bark elm cutting I had....His stuff was really well done and as healthy and vigorous as I've ever seen...hes in Georgia and out of my zone. Would be a good frame of reference
BTW...aren't you the one that told me you kill junipers