We walked last August from the coastal suburbs of Porto to Santiago and enjoyed it. We did the sendra litoral/coastal route as far as Redondela and then merged into the central route. (We had previously walked the central route.) We stayed in hotels, and my wife had her pack transported. It was busy and warm on the central route – the coastal route was cooler and less crowded – but not unbearably crowded. As the previous poster noted, there were lots of twenty- and thirty-something Spaniards walking the last 100 kms of the central route. We reserved a day or two in advance (maybe a little farther in advance for the weekend) and had little trouble finding places to stay.
We always love Pontevedra, and encountered lots of unexpected things of interest along the route: the beaches in the Vigo suburb of Nigrán, a crew regatta in Redondela, the hot spring outdoor hand laundry (lavadero termal) in Caldas de Reis; and the really beautifully updated and renovated Rosalia de Castro House-Museum in Padron. Enjoy it!