How to use ML to forecast sales of a brand new product
You could use Bass or Gamma/Shifted Gompertz method to do that. You could use  diffusion package in R. 

Here an example (it is form documentation of the package) : 

library(diffusion) 

fitbass &lt;- diffusion(tsChicken[, 2], type = "bass")
fitgomp &lt;- diffusion(tsChicken[, 2], type = "gompertz")
fitgsg &lt;- diffusion(tsChicken[, 2], type = "gsgompertz")
# Produce some plots
plot(fitbass)

plot(fitgomp)

plot(fitgsg)

fc_bass &lt;- predict(fitbass,h=20)

fc_gomp &lt;- predict(fitgomp,h=20)

fc_gsg &lt;- predict(fitgsg,h=20)

plot(fc_bass)

plot(fc_gomp)

plot(fc_gsg)


The only disadvantage of the methods is that they do not take care of seasonality of the sales of the products.