over 4 years ago - Shurenai - Direct link
There is no command to just make the current day a blood moon as far as I know. But since it sounds like the server and it's settings are within your control, there is a way to do what you want...albeit a slightly inconvenient way.

Just turn off horde nights whenever you aren't both on; And when you will both be on set the blood moon frequency to 1; This will result in a horde night every day, including the current day. If you'd like to have a day or so of prep first set it to 2 instead. However doing it this way means you'll need to then go change it back to off after the blood moon.

Blood Moon Frequency sets the next horde night X days forward based on the current day.