Old Velvia 50

I have 5 so rolls of old Velvia 50 they are likely 6 years plus old and not stored cold. Is it worth shooting the film? And if I process it myself with the Arista kit from Freestyle what adjustments to time would I need to make?

Any leads would be appreciated, Thanks

Use one roll for a snip test. Shoot bracketed exposures emphasizing overexposure. The film is likely slower than ASA 50 owing to its age. The MacBeth chart and some colorful objects or a person are your best subjects for testing. Snip and process a foot or so of the test roll and then make process time adjustments accordingly for a couple of more tests.

You will likely find color balance is somewhat off as well, but perhaps not beyond being usable depending on storage conditions.