The amendment option with Sprintax will be available for 2025 at the end of March, and you can amend your tax return as soon as you have all the required documents (such as income documents and the original tax return filed).
Please note that there is no deadline for filing amendments, so the April 15th deadline does not apply to your situation.
Warning: It is not recommended to amend your tax return before receiving your refund, if you were expecting one.