They are planning to get them up and running till winter, but I don't know enough to have an opinion on whether this is achievable and if not how much of a problem that would be and if those three nuclear plants would make a difference.
"Title: Maintenance on eight French nuclear reactors delayed by strike ... French nuclear availability is currently at 51% of total capacity with 26 reactors offline for maintenance."
[1] https://www.reuters.com/business/energy/edf-says-strike-hits...