In May there will may be 100+ pilgrrrims starting each day.
So the Mountain Express that
@trecile suggests is a good option. The consequence is that you will pass through Roncevaux the next day and continue towards Pamplona.
And
@VNwalking has suggested stopping at Valcarlos on the first night. The steep rise will then be on day 2.
Another option is (the 78 year-old says nonchalantly) is to increase your confidence in the strength of your body and mind.
Without knowing what your training regime has been, I suggest you work up to, before stopping for breakfast/coffee/whatever:
1) 10-12 km
2) 400 metres of elevation gain
And all gear you will take with you on your back.
Getting elevation gain as part of training is awkward in most places. One work around is using stairs in multistorey buildings. A particular advantage of going up and down stairs is they better exercise muscles from knee to hip than walking on paths.
Then there is finding a technique (that works for you) to just keep going (stopping for mothing) when going up (and down) hills.
A technique that seems to work for me includes the following:
1) Avoid casual stops while underway
2) dress for the entire ascent (or descent). For example if setting off about daybreak dress for mid/late morning: you can expect to warm up quite quickly (i only use gloves for my fingers)
3) on the steepest sections take short (very short) steps - about 100 mm to 120 mm. This means you dont have to waste energy lifting you legs very high.
4) breathe in on one foot fall and breathe out when the other foot hits the ground - this can help you maintain a steady rate
5) increase the step length of less steep sections.
Using that technique, together with the fitness from three weeks of walking from Le Puy, allowed me walking at a snails pace, to pass everyone going up to Leopoeder.
The Pyrenees is not the only hill. As well as the ups and downs after Astorga and the vicinity of O'Cebreiro there is hill work much of the way to Burgos and after Sarria and Portomarin. So specific hill training is not a waste of time.
You will need to work out you own regime for yourself over the next 14 weeks. My suggestions are intended to help you complete you intended pilgrimage without fitness issues.
Kia kaha (take take, be strong, get going)