You can go ahead and have him taken into the groomers for a "first cut" visit, perhaps within a week or so. This will give you plenty of time to call around for pricings, and to give you an idea of what would be the best place to take him to. They can help you decide how much coat to leave him with, and will be a good way to introduce him to the world of grooming. Take him to a place that has experience with poodles, and will be considerate of his newness to bathing and clippers.
You won't be allowed to take him to a groomers until he has been given all of his shots, though, so the appointment will have to revolve around his shot record.
His hair can be as long as you want it to be, but you must keep up with daily brushing in order to prevent matting. Matts can be very painful to brush out, and may have to be shaved down in some cases.
