I'd recommend a good 3 months overlap, tell everyone you can think of your new email address, then run for at least 3 months and whenever you find yourself having to log in with your old address, or see email coming in on it, make a point of changing it immediately for that sender / service.
I stopped using my ISP email about 10 years ago, and STILL see some stuff coming in on it! Nothing important, mind you.
One final recommendation....I have my surname.co.uk as my main personal email address, which is great because it's unlikely to every change, even if I stop or change the name of my business!
I just checked, and your surname (being quite common
) isn't available. However, if you're happy with where you live and don't see yourself moving any time soon, hasholme.co.uk isn't registered and so for a few £s a year you could have
[email protected] (or hasholme.uk - 2 for 1 for the first year with some registrars just now). This might have more longevity than an email addressed based on your mobile discos? They could always be forwarded either way, so it'd wouldn't mean another mailbox to check...