GMAT score only plays one part in the admission process. If you have a wealth of experience (especially at the management level), it might more than make up for a low GMAT score.
Since there's an unknown element as to whether the school might actually admit you to the program, there's no harm starting a bit of GMAT preparation now - just in case...
Nothing that you have a family, you might need to do a balancing trick between prep and family commitments. Talk to your wife and maybe your kids about this. Let them know that you will be occupied a little while for the next month or so. There are several test-takers here who have a family just like yours but they made it too. For my case, I took to studying at late nights after my wife has gone to bed and slug it out for a month before settling into an alternate day pattern.
For starters, you might want to see which area you need to brush up on. It will make prep easier to spend time on things you are weak, and less time on things you are good at.