Lapsehoolduspuhkus

The question is the following:
If my son is 2 years old at the moment. I went back to my old job after lapsehoolduspuhkus two weeks ago. By law, I have a right to be on lapsehoolduspuhkus until my child is 3 years old. If I want to use the remaining 1 year of my lapsehoolduspuhkus can I do it at any time? Or if I returned to the job after 2 years instead of 3 I loose the possibility to use the remaining year?
Thank you for your reply.

Although You're already back at work You still have the right to stay home. Your right to stay home ends at the moment Your child becomes 3 years old.