Unfortunately you can't.

CRA requires that tuition credits be used to lower your tax payable to zero. This takes place before other non-refundable credits such as donations are taken into account.

Depending on the type of other non-refundable amounts you have to claim, you may be able to carry forward some of the credits. Donations, for example, can be saved up for up to five years. You're also allowed to choose your 12 month period for medical expenses (as long as the 12 months ends in the tax year) so if it's better, you can enter your 2017 medical expenses on next year's return.

Here's a link for more information on the 12-month rule for medical expenses: https://turbotax.community.intuit.ca/replies/2647801