Imagine you had a genuine injury that had prevented you from working for 2 weeks. You then improved and over the weekend and realised you were probably fit for work on the Monday.
If Monday was a particularly challenging day work wise due to work schedule, and could be a real baptism of fire in terms of returning after an injury, would it be unreasonable to return on the Tuesday instead, to avoid unnecessarily stressful first day back (and to avoid potential feelings of not being able to cope)?