Apple Watch quickly sold out of its initial launch allotments, and Apple Watch bands are also experiencing a shortage online. A glance at the Apple Watch bands page on the Apple Online Store reveals most bands will now be shipping in May. As of this writing, the 38mm Link Bracelet ($449) and 38mm Milanese Loop ($149) have 2-4 week shipping estimates, while the 38mm Modern Buckle is completely unavailable, in all sizes. It’s currently unclear…