Unfortunately, there's no clear answer to your question. Has the school that releases decisions earlier posted a deadline for you to accept an offer of admission? (If they release decisions around Jan 1, then they should give you a few weeks or maybe a month to let them know?)

Whether or not the school will extend the deadline completely depends on the school - some schools may provide a short extension. But, from my experience, I think it's rare for a school to give you three additional months to make a decision. If you'd rather wait for your top choice school, then maybe you should apply in a later round where you can consider your offers together and make a decision?

But, the best answer to your question about extensions would have to come from the admissions office.

Good luck!

Julie