Best Buy appears to be one of the only stores with actual stock of the Apple Pencil. At Staples, the Apple Pencil is listed as "Coming Soon" with stock arriving on November 25, which is the only other upcoming availability date. MacMall is accepting orders, but shipments won't arrive for three weeks, while B&H Photo is also accepting pre-orders without an estimated shipment timeline. At Adorama and Walmart, the Apple Pencil is listed as out of stock.
On Apple's own site, the Apple Pencil has an estimated shipping date of four to five weeks, with orders placed today arriving between December 23 and December 30 at the earliest. Apple retail stores have been receiving shipments of the Apple Pencil, so the best way to get one immediately may be to check in regularly at a local Apple Store.