I know this has been discussed before and has been the subject of a bit of confusion.
My current reason for raising it again is that my Mk3 CVT has just had its 25,000 mile service (at 22 months) and has had it's CVT fluid changed. Item 24 on the service sheet "Replace Transmission Fluid. CVT" is ticked even though the words next to the box say "Every 50,000 miles or 5 years, thereafter every 37,000 or 3 years". When I picked it up the Service staff confirmed verbally that it had been done, but I hadn't noticed the 50,000 mile bit at that point so didn't ask.
My last Jazz, a Mk2 CVT, was effectively scrapped at 65,000 miles because the CVT box failed and it was going to cost over £5,000 to repair. It had had CVT oil changes at 25,000 and 50,000, and then another at 60,000 because it had got noisy. So I am very sensitive to CVT issues and maintenance.
I am not sure whether mine has been done this time because of my asking beforehand, and my history (same dealer), or whether it is meant to be done at 25,000 anyway, in spite of what the service sheet says.
I have a memory that the interval was changed fro 50k to 25k at some point, so maybe the paperwork never got updated.