This depends on the task that you need to get done by your professional. If you need a few simple repairs for your mailbox, then your Tasker may need only a few minutes (around half an hour) to get the work done. If you need a total removal, replacement, and installation process done, though, then it may take up an entire day or more. If you need several mailboxes installed, then it may take even longer. Be sure to discuss all the details with your Tasker first so that you can manage expectations.