You could probably get away with taking cuttings at any time of the year but you must treat the cutting with a bit of care. Traditionally, late summer is the correct time....oh those warm days sitting round a table taking thousands upon thousands of named varieties cuttings for Brighton Parks dept are just a distant memory now.
Anyway, if you were to take cuttings now, they would appreciate a little bottom heat if you can but not essential. You mustn't over water them though. They hate humidity and will rot if you keep them too cold and too wet. A good compost of 50/50 cutting compost/pearlite or vermiculite is ideal....ive rooted them in neat pearlite before. A nice north or east facing window sil is ideal for them...they don't mind a bit of sun but you obviously don't want them to get too dry.
Good luck,