woody stems do take longer to root than new flexible stems.. as for age of the mother, i always start from seed and wait till the mother shows sign of its sex wile stil in vegitive state. normally between the seventh to tenth node.. never take clones before the plant is 50-60 days old, that way it should be mature.. you can clone a plant earlier, but you will not get the full potential of the plant as its not mature..once in a wile ill take a clone earlier but only to root it under 12/12 light to find the sex, but then after i know the sex its a throw away..clones i take from mature mothers are rooted under 18/6 light sced, once rooted usually after 7-10 days in my clone king, i place each clone into 1'' rockwool, placed into 4''x4'' rock wool blocks and onto my flood n drain table.. veg time depends on strain, some sativas can go wright from rooted clone into flower wile indica dominant strains need at least 1-2 weeks of veg time if its a strain that does not stretch much in flower i give it 3 weeks of veg before its put into my bloom room.
i however do not keep mothers after the clones are taken.. i keep the best 2 or 3 clones to be new mother plants.. after say 2 weeks wile all the other clones go into the bloom room the 2 or 3 best clones(mothers) stay in veg.. when my bloom room is 4 weeks into bloom, those mothers have now had 6 weeks of veg time and are ready to be cloned..this way the clones taken have just enough time to root then get 2-3 weeks of veg and by the time my plants in bloom are pulled,the clones are ready to go into the bloom room and 2-3 new mothers take their place.. doing it this way my mother plants are never around long enough to recieve any stress or degrade, if anything ive found they improve as the strain evolves or adapts to my grow style or my enviroment.. i had ran a nirvana misty strain this way for 7 years, i was probably into the hundreth or so generation of clone of clones from the original seed mom and imo the clones wher better than the original seed mom, they finished flowering in 50 days, wile the seed mother and first few generations of clones took 56 days to finish..they also had better structure, wile the smell, crystal production, and yields wher wroughly the same..that misty strain was very tough, i tried multiple times to get one to get pollen to create S1'S, the rhodilisation method, temp stress, nute stress,ph stress, light stress, even coildal silver,, i never could get that plant to produce any viable pollen.. after 7 years i lost it,, i had bought a batch of clones from a dispencery that brought with it a spider mite infestation.. now that strain is no longer available.. now im currently growing multiple strains but my best is T.H SEEDS BUBBLE GUM, ive been growing this strain for almost 3 years now using clones of clones for mothers.. this time however i used tiresias mist on a branch of a single plant and created S1 seeds so ill never lose this strain..i also NEVER buy clones or allow any way that can introduce bugs into my garden..lesson learned..