I've found if you let 8 or 9 charms roll around on the chain for a while it helps relax the links so it becomes about 1/2 cm larger. All my bracelets are 17.5 but if I hold them up against one another they are all different lengths.
When I wear my bracelets I like them to stay on my wrist just resting above the lowest thumb joint when my hand is down at my side. I don't like it if they are big enough to roll off my wrist without undoing them. It becomes a personal preference. I went with Pandora's suggested size for my wrist and I am very happy with it.
thanks for your response,
i think i took the good size but i always have doubt so...i dont like to wear my bracelet too loose so i think it will be ok,
do you think is it ok to put all the charm in the middle section or is it better to mix it in the three sections??