Delay signal according to normal distribution
Normal distribution regardless of whatever mean and variance you provide, can still produce large positive and negative numbers(albeit with a small probability). 

Do you want to specifically use normal distribution, or all you need is a random delay generator? If latter is the case, you can use rand() from MATLAB, also you could use randi if you need integer delays. 

Also you could use something like this to generate uniformly distributed random numbers in a specific range.