Let's be direct: automating a timesheet by entering a single date is a good idea, but the fact that someone has to ask how to do it in a traditional spreadsheet tells you everything about how far that tool has fallen behind. The poster, tasked with building a fillable form for a small business, is working with a pre-made template that offers no functions to build on. That's not a limitation of their effort. It's a limitation of the tool itself.
Here's what this means in practice. In a conventional spreadsheet, generating an entire month of dates from one starting cell requires formulas, conditional logic, and careful error handling. The person building the form has to know how to write those formulas, test them, and then hope no one accidentally breaks them. And every month, someone has to update the start date again. That's not automation. That's manual work dressed up in a grid. The employee entering their hours shouldn't have to think about whether the date cell is formatted correctly or whether a formula got overwritten. They should enter a single date, or better yet, nothing at all, and see the rest of the week populate reliably.
Our take is straightforward: if your timesheet process requires a user to manually script date logic, you've outgrown the spreadsheet. Not because the spreadsheet can't do it, it can, with enough effort, but because the effort is misdirected. The goal isn't to make Excel work harder. The goal is to make the person's work disappear. An AI-native approach would let you describe what you need, "start the month on the first Monday after January 1st", and have the tool build the structure for you. No formulas to write. No cells to protect. No tutorials to follow.
For this small business, the real opportunity isn't in finding the right Excel trick. It's in asking whether a fillable form is still the right container for the problem. The employees don't want to fill out a form. They want to log their time and move on. A system that predicts the week's dates, remembers last month's pattern, and adjusts for holidays without anyone typing a formula would save more than clicks, it would save the cognitive load of maintaining a fragile document. Start by automating the date logic. But don't stop there. Let the tool handle the structure so your people can focus on the work that actually needs their attention.