I'm writing a novel for young readers, but had just realised I've messed up my time lines. So far, two days have passed for some characters, but four days for others. Would giving the main characters a couple of days to hang around slow the action too much? Is there any way to fix this?

I would first of all suggest you use writers software like writers Cafe(if interested ask me I tell you where to get it), and instead just hang around add pieces that would make séance later. Don't just go oh "past few day were so boring that I don't even know what to mention, without falling asleep", if you do this on computer you always have chance to plug in information. I am old style so I like to do things on paper, yet I consider that work more of draft, and usually I use writers soft that try's to cover most details. Don't worry its not cheating your effort, writers cannot remember everything, it is just a way of organizing things.

Believe me, I don't write "Last few days were boring." Actually, I doubt writers software would have caught the time line thing. One of my characters was in hospital and mentions tests that were carried out. Anyone who knows medicine would realise those tests took time. But so far, no-one else has noticed, I haven't been counting out the days.

I thought it would not help too until tried. My part was to suggest and your is to accept or decline.
For some reason you sounded offended, my apologies If I did, that I did not intended to.