regardless of you want to continue on top-up or look for job, then you should become member of an A-kasse and register as graduated at latest 2 weeks after graduation.
By doing this you can start getting unemployment benefits ("dagpenge") when you want up to two years after graduation. So regardless of which of the two ways you decide to go, you will be able to get dagpenge, if you find out it was a wrong decision you made. For example if you have to drop out of Top-Up, or you start job but have to stop/get fired after for example 3 months.
So you can always use your "graduate-rights" up to two years after finishing study. You do not need to meet further requirements.
Anders Weber, www.a-kasser.dk