Certified GKH Gardening Expert
Adding those sources of calcium will be a guessing game. If you, instead, foliar spray with epsom slats, you will just follow the instructions on the bottle.
If you choose to use the methods that you describe, just add a little every week until the plant starts to produce a fruit with no rot on the end. I would use, just, one of the methods, though. Not all three.
Here are some articles that will offer solutions to the issue: