For one party, it takes effect on 15 days, that is, if you are the plaintiff, if you do not appeal within 15 days after receiving the judgment of first instance, then the judgment in the judgment takes effect. You lose the right to appeal on the same matter. For the defendant, if there is no appeal within 15 days after receiving the judgment, it will be unfavorable for the defendant's judgment to take effect and the defendant will lose the right of appeal in this case.

So you need to see whether the judgment is good or bad for you. If the verdict is against you, then you don't have to care whether the defendant appeals, you should appeal as soon as possible.