Your point is well taken, nut I think the delays in testing are denoted in the time constant to the first inflection point. Once testing gets going it appears to be fairly consistent. So it would make sense that it would produce a discernible time constant. However, this is indeed an assumption of this analysis.
Seems to me that the test rate might be impacting the numbers we are all considering and in that case might be misleading if trying to compare totals without calculating the difference in the test rates. Another factor in all of this is Mother Nature and when she arrives in warm enough fashion to expedite the end of this virus. Since we are getting hit after the others and our weather is closer to spring, we might have less to worry about. Your efforts are much appreciated and certainly give us a slightly different perspective of the time frame.