Any income is reported when paid. Wildfire relief payments were designated as tax-free, but still need to be reported, they will be reported on your 2025 return. Payments from charity would usually not be taxable (although there might be exceptions)--they would be taxable when actually paid.
The loss can be deducted on your 2024 or 2025 return. However, at this time, it's not obvious which would get you paid faster. If you never filed your 2024 return (are late or have an extension) then your loss will be handled faster filing on the 2024 return. But if you already filed your original return, I don't know if an amended 2024 return would be paid faster than an original 2025 return (because of how long amended returns take to process).
You also have to account for any reimbursement in your loss calculation, so if that is not final, you should probably wait to claim the loss, because if you claim a loss now (on an amended or original 2024 return) and then your loss ends up being different because of adjustments, that gets complicated to correct.
