People tend to check in during these times:
Official Transport for London page. TfL works to keep London moving and make transport accessible for all.
You can get District Lines (Green) to Edgware Road and also City via Victoria
Stand near the stairs on the platform if you will be leaving the train at Notting Hill. On arrival you'll be near the exit and will avoid the mass disembarkation crowds... :)
If you want a Metro, get here before 8:45!!!