Check this file.
I used a string to store the sizes of the waves, cause it's faster, but you should use an array. Also, the time between waves is constant, you should make it variable, in that case use the same array to inform the intervals... Like wavesArray = [[wave 0 size,wave 0 interval],[wave 1 size,wave 1 interval],[wave n size,wave n interval]]
In case you never used arrays, you can access tyhe info in an array with wavesArray.At(x,y). So, you would use wavesArray.At(currentWave,0) for the size and wavesArray.At(currentWave,1) for the next interval.
Hope this helps...