The sooner they’re digitalised the better. The main barrier to doing that these days is having access to a VCR (looking on eBay or asking friends or relatives might be your best bet here) but once you have one, you can buy a USB adapter, and they usually come with added software to make the conversion. Alternatively there may be services that will do it for you for a fee (depending what country/area you’re in)
Why is this important? Well, you might be able to preserve media that is of interest to other and would otherwise be permanently lost, but a more common scenario that sadly happens all too frequently is that you’ll wish to revisit a home video and find that the quality has degraded significantly, to the point it is difficult to watch.
The sooner you act the better. Please, if you have video that is important to you, act now before it is lost forever. I have in-laws who took the time and effort to transfer their film to VHS in the 90s, only to then leave it to degrade, not realising that this would be the case.
It’s super dependent on how they were stored. I have 30 years old VHS tapes that are fine.
Keep them out of sunlight, high humidity, and preferably in a climate controlled place (not your basement)