To be fair, the President and the administration had access to a lot more intel. I don't expect a governor to know everything that was going on.
There were a bunch of things the admin could have done to try to slow down the transmission without causing a panic. By then, Trump was more worried about hocking Hydroxychloroquine, then actually working with scientist to control the virus before it became a series issue.
That tweet looked bad less than a month later. How did the whole down playing work out?
Before you ask me what more he could have done, I can think of couple of things that would have helped
1. Not ignore the initial reports about the virus, when it was primarily in China and hadn't quite hit the US yet.
2. Work with the WHO to find out what exactly was going on
3. Immediate national Contact tracing
4. Use the COVID tests that were already known to work and not waste months and tax dollars trying to develop one from scratch (or use the WHO tests until an American one was valid). It should be noted that the Governor of Maryland said fuck it and bought some of those very tests that Trump said weren't no good.