And if it can be reduced by 60%, we will see exponential decay instead of exponential growth. (assuming R=2.4 is the average number of people each victim infects, which is a number I've seen used a lot).

It seems plausible that social distancing can reduce human contact for the average person by 50%, and for people with some flu symptoms by 80%. All this is to agree, the growth rate is by far the biggest factor in getting an estimate of peak impact.