@sytse: If this (BGP + ASN + /24 IPv4 + /n IPv6) is your plan, I'd encourage you to get started on the process now.

Go ahead and apply for your ASN now and an IPv6 allocation. Then start working on the paperwork for an IPv4 allocation. Because there is no more IPv4 to allocate you'll have to go through the auction process and then the subsequent transfer process.

You'll easily be able to find a provider that can give you a /24 if you buy transit from them, but you don't wanna go through the trouble of renumbering into your own IP space if you can avoid it.