title: (Google Sheets) How do you get cells to alter based on a certain date?
body: <p>I'm looking to create a spreadsheet to get a grasp of what my personal finances are saying. Part of this obviously involves putting in income from my job. While I know my shifts in advance so I know how much I will be earning on any given day, I won't actually get the money until the end of the month.</p>
  <p>I've created a cell called 'bank balance' based on my current savings, but obviously I don't want to have to physically update this every time I get paid so I'd like to just be able to give Sheets a date where it can update that cell itself based on my payday.</p>
  <p><strong>For example:</strong>
  I start off with £100 in my bank account on January 15th. I know I'm going to get paid £400 on January 28th (last working day of the month). I don't want to input that on Jan 15th as that wouldn't be an accurate reflection of my finances. So I input something that tells sheets to add that £400 on to the bank balance cell on Jan 28th for me.</p>
  <p>[The example sheet on January 15th]<img src="https://i.stack.imgur.com/KmSJJ.png" alt="1" /></p>
  <p>[The example sheet on payday January 28th after automatically adding on the £400 to the bank balance]<img src="https://i.stack.imgur.com/AbNxi.png" alt="2" /></p>
  <p>I've currently got a separate cell for 'work income' that I want to apply this function to (I.E. so that I can tell the sheet to add the total 'work income' to 'bank balance' on payday) but I'm not sure where to go from here.</p>
  <p>I've got similar issues with subscriptions leaving my account on various days of the month but the income is my higher priority.</p>
  <p>Any help with this would be greatly appreciated</p>