If you have kids you know this...if you've had kids and they are grown..you still should know you just might not remember. And if you don't have kids you probably don't know this but you should.
I'd say this mostly applies to moms with babies. If you make plans with moms with babies...don't change those plans to a different time at the last minute!! If you say your going to be there or do this or do that at a certain time..stick to that time! You see moms with babies have to go with their babies schedules. And NAPS ARE VERY IMPORTANT. So if they say their baby needs a nap first..don't expect them to just wake their kid up in the middle of their nap just so ya'll can go somewhere at a certain time. Just don't expect the moms to be ready until after their baby has napped...cuz most likely, the mom uses that naptime to get herself ready to go. Cuz its almost impossible to get ready when baby is awake...especially a mobile baby.
Also, don't try to make last min plans with a mama of a baby either. That is very difficult on a mama. See her days are planned out with feedings, and awake time and nap time and what she can get done during nap time, etc. SO if you spring something on her last minute its gonna cause a stir in her whole day and that could be a very bad thing. Seriously.
So please take this advice and use it wisely. Otherwise your gonna see a mama have a huge bitch fit and lose her cool! And believe me, you don't want to to do that!