Yes, you need to enter those. TurboTax asks for these in anticipation of needing to prepare Form 8606 if Form 8606 is required to be included with your tax return.
Since the regular due date of your tax return is before the deadline for IRA custodians to issue Forms 5498, these values are normally obtained from your year-end IRA statements and from your transaction statements showing distributions that were made near the end of the tax year but were deposited as rollovers or recharacterizations early the following year. The rollovers and recharacterizations for 2018 not deposited until 2019 will be reported on your 2019 Form 5498 that you won't receive until about a year from now, so you don't wait for that to file your 2018 tax return.
