If you need the tuition credits to reduce your "tax payable" to zero, TurboTax will apply what is needed. "Tax Payable" is different than your refund or balance due at the bottom line of your tax return.
This means if you have to use any of the tuition amounts this year to reduce your tax payable, they will be applied to your return automatically by CRA, even if you attempt to carry them forward.
TurboTax will apply the needed amount to reduce your tax payable to zero this year and carry forward any excess to future years. Then CRA will automatically apply as needed. If you can use all your credits in a particular tax year, you are required to do so. You cannot spread them out over a number of years or wait to claim them.