exactly. Turn up with everything and give it a go. I've never seen anyone saying they've been refused the conversion but then again I don't know if anyone has ever tried.
Your inheritance will have come from somewhere, get whoever paid it to you to write a letter stating the provenance. I'd also be prepared to show how you will be able to support yourself for the duration of the DTV 570k baht isn't going to keep you
rather than cancelling a DTV will any of them do the conversion to another visa type as per the original DTV official announcement? Just wondering why anyone would want to cancel rather just convert?
A new year will make absolutely zero difference. I would say you will be allowed to enter providing you have no other history but will only be allowed a 7 day extension at most. Best to have a ticket out of Thailand, 20k baht in cash and accommodation booked. If you do have history in Thailand all bets are off