How do I apply for a re-entry visa before leaving Thailand and do I need to notify my residence if leaving before 90 days?

The user has a multiple entry retirement visa and is seeking clarification on two points. Firstly, they need to know how long before leaving for the UK they should apply for a re-entry visa, including the cost and process. Secondly, they are unsure if they need to notify immigration of their residence if they leave Thailand before the 90-day notification period is due. Various comments confirm that a re-entry permit can be obtained at any time and costs 1,000 Baht for single entry or 3,800 Baht for multiple entries. Additionally, if the user leaves before 90 days, they do not need to report their residence, as the 90-day clock resets upon re-entry.