You can already see the number using the earnings calculator.
For the first 30 days this score will show 100% though. I’m not entirely sure when those first 30 days are over. My nodes still show 100% everywhere. But I’ve also had barely any down time. The reason for this is that the satellites don’t want to punish nodes within the first 30 days, because not enough data is known yet. It should of course still show the actual score and just omit any punishments, but that’s not currently how it’s implemented. Either way, you can monitor the uptime there until it’s shown on the dashboard (which I’m sure will be soon as well).