As Soon As Possible
Sure you can leave the mistake, fooling yourself into thinking it doesn't matter. No one will notice. It isn't that big. Who really looks that close anyway? But you know the truth. Every time you look at it you are going to see the mistake. Ripping it out as soon as you notice the problem is best. Continuing to knit is just going to give you more to rip out.
Maybe You Can Fix It
If you can fix it with out ripping all of your knitting down to the mistake, go for it. Some times it is possible to drop a few stitch down to the mistake, reknitting those correctly. This can even be possible with mis-crossed cables. I recommend having a crochet hook or dpns handy, and possibly a removable stitch marker.
There is Hope
The good news is as soon as the mistake is fixed, however you choose to do it, you can get to back to the fun part. Knitting. That is why we put ourselves through this after all. Because it is supposed to be fun.
Just a reminder that if you leave the mistake now, you might find yourself having to rip out even more later. Ask me how I know!
Check out these classes at Craftsy: Save Our Stitches, Fixing Lace Knitting Mistakes with Laura Nelkin and Save our Stitches, Fixing Knitting Mistakes with Ann Budd. Thanks for supporting this blog through affiliate links. I appreciate it!