Well, there are different approaches for this, i would recommend this (I did it just over one year ago).
Skip the (longer) route diversion, follow the old camino, it is still fairly well marked, it does not add any tarmac to the total mileage, since the river path is only a diversion that makes the route 8 km longer
Consider spending the first night in Lafuente, albergue with a donativo, the hospitalero can provide (or at least did so last year) dinner and breakfast for a little more money. The Hospitalero was a lovely Polish fellow, Michal, last year.
Cicera has a public albergue too, and a bar, and it is a quirky little village
Cabañes has an albergue too, only you have to ring in advance. Beautiful place
Potes has a great albergue and the most helpful tourist information office ever.
This year is meant to be some official Jubileum year for this camino. so it is quite crowded.
Signposting can be a bit funny at times, but you should be able to make it. The best part is, incidentally, once you pass Potes and go on to Espinama and Picos de Europa mountains. Unbelievable!