If you are certain that the payroll deductions in February 2019 were designated as HSA contributions for 2018, included in box 3 of your 2018 Form 5498-SA, do not enter these as personal contributions. In the HSA section indicate that your employer told you about other contributions, then enter the amount of employer and payroll contributions made in 2019 for 2018 so that it is included on line 9 of your 2018 Form 8889.
Next year when you prepare your 2019 tax return, the 2019 W-2 will include in the box 12 code W amount the contribution made in 2019 for 2018. In 2020 TurboTax you'll need to say that your employer told you about other contributions and identify the same amount as contributions made in 2019 for 2018 so that this amount is not included on line 9 of your 2019 Form 8889.
