Why bother estimating? you have the checkboxes, now just get to work. If the pace of checking those boxes is slow then you can start cutting things out. Estimates are for managers, much better to just ship it already.
But you are right that estimates are for managers. Managers should watch their reporter's progress and use that as evidence to build evidence. If the first task of 20 took 1 week, it's a 2year project. Update estimate as time and progress and work remaining increases.