Was shorting tesla at market open a good strategy?

I'm a learning trader and given the whole trump salute thing, I assumed tesla stock would fall at market open. I shorted one stock on the investopedia trading simulator and ended up making 12$. Since I'm learning, I don't know if this was a calculated move or just a fluke, would love to hear your thoughts. Also please suggest a better simulator than investopedia's, it works really slow at market open.