As far as I know, TurboTax does not ask about the timing of contributions that you personally deposit; it's not relevant information. I think this HSA contribution timing question only applies to contributions made through an employer who reported a code W amount in box 12 of your W-2. You would need to ask your employer about the year for which your contributions being made through payroll deductions are being made.
Also, make sure that are not mistakenly entering HSA contributions as IRA contributions. TurboTax *does* ask about IRA contributions made between January 1 and April 15.
