As I pointed out in the related thread Avoiding xpub+derivation reuse across wallets, in a UX-friendly manner - #7 by sjors, I’m inclined towards m/87'/0'/0'/[UNIX-TIME]/{0,1}/*.
BIP 338 Wallet Policies for Descriptor Wallets could be expanded to add T, the wallet birthday timestamp. It has to be the same everywhere, e.g. tr(musig(@0,@1)/T/**,{and_v(v:pk(@0/T/**),older(12960))} is 2-of-2 where @0 can unilaterally sign after 3 months.
You could also use block height H, since it’s a smaller number. But not everyone has an intuitive feel for block heights. It’s also much more likely that you’ll recognise a date even in the distant future.
Either T or H also make for a nice rescan hint.