I am three quarters of the way through my first attempt at a children's novel and was just wondering when exactly should the plot kick in? The real story doesn't begin until chapter 4, with a few clues, hints and suggests given in the prior chapters. Acceptable? The early chapters are still entertaining though, I think. Ha.
If it's something you are hoping will be published one day, keep in mind that an agent or publisher will be looking at the first three chapters in the first instance. If those chapters have little to do with the plot outlined in your synopsis then they may decide to read no further.
If it was my book I would rearrange the order of the chapters so that there is action related to the central plot in the first chapter - first page ideally.
I wouldn't delete the original first three chapters though. All the most entertaining bits can be recycled into this or other stories.
Hope that helps.