I used water germination because it needs so little space and I can see immediately if seeds start to sprout. The seed was fresh but I was worried it might not be viable.
I put these N mirabilis seeds in a clear container with pure water on the windowsill in bright indirect light. Checked the jar daily and gave it a gentle shake. Ambient temperature mostly between 15°C to 26°C (59 to 79°C) at the coolest time of year here. (Slightly warmer might be better but didn't have a heating system.)
On day 33 the first tiny green sprout was visible. By day 45 most of the seeds had germinated, far too many to count!