HI Dalglish60
The starting date of your PIP claim is the date on your PIP claims form providing you posted it back before the due date.
Your ESA will stop when you reach state pension age, you can contact the Pension Service 4 months before your retirement date to apply for your State Pension, you can also apply for Pension Credits 3 months before you retire if eligible;
www.gov.uk/pension-credit/eligibility Gary