It's a bit early. Between late September and early spring is best.

Do a Google search to find masses of info on how best to do it.

Normally I have taken the cuttings when new growth starts and it is the soft wood cutting I take - about 4 inches and remove all the bottom leaves and leave only the top 2 -- dip in rooting powder and pot - cover with plastic bag, I use freezer bags - and secure with elastic band ensure the bag does not make contact with the leaves - it takes about 2 to 3 weeks to take root - but keep out of direct sunlight while taking root - I have had no trouble by doing it this way

They are quicker to root in spring but you can take them now if you can find a shoot without any flower buds. If there aren't any at all try taking out the buds you can see, and pinch out any more that appear while you are trying to root the cutting. Cut the stem with three pairs of leaves just below the third pair, then remove the lower two pairs.
Then you can either pot up the cutting(s), placing them near the edge of the pot, and cover them with a plastic bag or similar to conserve the humidity - make sure the leaves don't touch the plastic- or you can just put them in a small pot of water and wait until roots appear. If you do the latter be very careful potting them up as the roots easily break off, especially with autumn rooted ones.

Sorry Triffidkiller, we crossed, but at least we said the same thing!

Thanks everyone