Leaving in SJPdP you probably will be part of a tightly knit group, which is one of the pleasures of the pilgrimage. When you skip ahead, you will leave that group. You probably will become part of a group when you restart, but it won't be the same.
If you start further down the route, you will become part of a group, but will not have experienced the Pyrenees crossing, and may feel a bit like an outsider.
As with many situations in life, you cannot have it all!! You will need to decide which social situation you wish to join and weigh it against the value of the mountain crossing. If there is weather that covers the Pyrenees in fog and clouds, there will be no scenery, just the muscle and joint aches and pains and maybe blisters.
Burgos is about 550 kilometers from Santiago, a comfortable distance for you to cover in a shortened four weeks. In Burgos you will be surrounded by the 200+ per day who have started in SJPdP in May, but you also will join the 15 or so who are starting in Burgos. You will know the newbies the next night as you stop in the same place! You can walk with the ones just starting, or listen to the anecdotes of those who started in France, and join with them. You will have nearly four weeks to find the most compatible pilgrims as you head for Santiago.
If you jump ahead to Sarria, you will find 360 per day starting there. The 200 from SJPdP will be there along with the 15 from Burgos, but they all will be strangers to you, not the ones you may have started with. The dynamic between those who have been walking for nearly a month and those who are starting is a bit strained, if I may be honest. You can find a lot of comments on that dynamic here in the Forum, so I would not characterize it for you. Just know that it exists!
Tough choice! Good luck with it.