Not aware of your walking pace, so not sure if this personal account will help you at all, though as we had a good couple of hours walking within Las Médulas before continuing on the Invierno, perhaps this might be of interest :
Day 2: Las Médulas to Puente de Domingo Flórez
Thursday 23rd June - started walking from Las Médulas at 11:08am arrival 1:28pm
Recorded distance 15.52kms (6.77kms of which were within Las Médulas) / 23310 steps walked /
over the whole day 19.8kms / 29671 steps / 80 floors
We woke reasonably early, and leaving our packs behind, ventured off to look over as much as we could of the Las Médulas area, which is nothing short of stunning, especially as we walked in the eerie early morning mist. The views from the Mirador ce Orellán are sensational. Having walked and seen a good part of Las Médulas, we returned to pick up our backpacks and head off for the relatively short walk to Puente de Domingo Flórez. With such a lovely name, I had imagined that it would be lovely place, though regrettably much of the construction of recent times is very utilitarian. We stayed at the very friendly Hotel La Torre, who offer a very good value 26€ price for peregrinos (double occupation room), and a very, very adequate lunch menu. We looked around the town and took advantage of the ATM before having an ice-cream from the very peregrino friendly Bar El Cruce and stocked up with 'provisions' at the Dia supermarket, conveniently located close to the hotel.
Day 3: Puente de Domingo Flórez to O Barco de Valdeorras
Friday 24th June - started walking at 07:31am arrival 1:15pm
Recorded distance 15.52kms (6.77kms of which were within Las Médulas) / 23310 steps walked /
over the whole day 28.19kms / 44445 steps / 46 floors
A reasonable coffee and croissant at the bar of the hotel before our exit, and an easy to follow walk across the bridge over the Rio Sil and a gentle rise to the path that will follow the Rio Sil. The beauty of where we were walking was only marred by my mobile continually ringing with folk calling with their reaction to the outcome of the Brexit referendum. Passing through Sobradelo, we avoided descending from our heightened position and so missed seeing the town centre and continued ahead, passing through the village of Éntoma, where some of the narrow streets had been decorated with flowers and coloured sand in celebration of the fiesta de San Juan. Within this small settlement there is a quite striking metal 'sculpture' made out of agricultural hoes, which seems dedicated to the Camino and which bids 'Buen Camino' to the passer-by. Very close to this was a bar, but, I understood that because of the fiesta in Éntoma , it was closed. Leaving the village we headed along a gentle path that descended and then ascended to Puente de Domingo Flórez where, this being the day of San Juan, much was closed. We headed to where we were staying, the Pensión Aurum, which is highly recommended, very comfortable, quiet and clean and just a few metres from the Camino. Our search for lunch resulted in a slightly disappointing meal, as our sought out places were either closed or full. The walk along the 'promenade' of the river in O Barco de Valdeorras is a delight, both for the location as well as for watching the locals.
It is a pity that your lack of time seems to prevent your commencing your camino in Ponferrada
Buen camino...