Slow down particle half way through

I’m trying to slow down a particle towards the end of the particle cycle and I’m not sure what to do. I have set up a blueprint for the particle and can use custom time dilation to set the speed I want but it only allows me to set the speed for the whole cycle not allow it to play at normal speed for the 1st half and then slow for the 2nd half. How would I go about doing this?