How many shorts need upload to start getting views?

If you want fast results about 5 shorts per day would be enough

Try with 1 per day, and increase gradually based on your capabilities, and as you go, you'll be able to see how many videos it takes for your own niche.
Each niche is different.

Well you need to be consistent on a daily basis and continue working even if you dont see any results .
The biggest mistake people do its they stop working when they see almost 0 views on short ,continue to work no matter how hard it is
Me i have the exact same problem