At ten weeks, sickle feathers are still too short to be visible except for parting the tail feathers and looking at the emerging feathers. Usually a sickle feather will be noticeable as the only curved feather emerging from the straight ones.
If your photo is of a cockerel, it's too soon for...
Sometimes you will be able to see a sickle feather shooting out from the bundle of tail feathers, and that is indisputable evidence of a cockerel. No pullet has a curving tail feather.