"By this calculation, Tesla would exhaust cash on Aug. 6". This is assuming they keep on selling any or negligible amount of Model 3's. Even if they only sell 100k Model 3 cars next year, their revenue will increase by $3.4B. Their aim is to sell 250k cars next year. They're a couple of months late. Shouldn't be a big deal though..
Bottom line: You have to spend money to make money. This is totally normal and expected. No need to worry unless the ramp up totally shuts down.