If you're new to knitting, you may have heard of the term "frogging" and not quite understood what it meant (or why it's called "frogging"). No actual frogs are involved!
"Frogging" is a knit/crochet term for ripping out your knitting and starting over to correct a mistake. Why is it called "frogging" you ask? Because you "rip it, rip it" which reminded someone of "ribit, ribit" - the sound a frog makes. Yep, that's the history behind the term (and we don't know who coined the term).
When should you frog? It is entirely up to you. If the mistake won't bother you, keep going. If it will, then start frogging :)