I went round over Easter --- half a day from Criccieth to Pwllheli then full days Pwllheli to Porth Neigwl, Porth Neigwl to Aberdaron, Aberdaron to Tudeiliog (a long pull) and half a day from Tudweiliog to Nefyn. Mostly stayed at the hotel in Nefyn and used the coastal bus to and from start/finish points. The tip of the peninsula is really impressive and there's a nice Indian restaurant - Bombay Joe's - in Nefyn.
You'll get supplies in Nefyn, Tudeiliog, which is only half a mile off the path, but then nothing much to Aberdaron, just a beach cafe at Porthoer Except for a few stretches between Porthoer and Nefyn the surface is already pretty dry; I hit bad mud only once (and sank badly).
Try to reach Hell's Mouth at low tide; I had to follow field paths round at high water, which was tedious; at low tide the sands are passable, though the entry or escape at the W end may be a bit iffy.