It's one thing to claim as Miller (I got Miller and Mason mixed up) .... but that so many are insisting on cllaiming on day one is quite odd to me.
Most folks should not be claiming DP1, therefore town should not expect claims except under specific circumstances.
Town should read a couple of mafia wikis regarding your role- many include some advice about playing that role. There are a few roles where it makes sense to jump out right at the start. MILLER happens to be one of these.
I'd say that it would be typical of town to agree to bring out character claims in DP2 and then most or all roleclaims DP3 but circumstances always dictate.
As I've said before, the value of claiming is to try to verify yourself as town. That value is seriously diminished when there are inactives like warren and cookie because we don't know if they would contradict any claim. Therefore, I recommend that we focus on activity DP1. Scum is strongly motivated to make credible claims early and buy some town cred. The fewer players out there checking the validity of early claims, the stronger scum's advantage.