When does the 100 night trial start? Simba - Odyssey January 18, 2018 13:21 Updated Follow Don't worry if you need to delay the delivery, the 100 nights start on the day you've received your mattress. Related articles Do we have to pay to trial the mattress? How does the 100 night trial work Where can I test a Simba mattress? I have a sore back - would a Simba Hybrid help? How deep is your mattress, will my sheets fit? Comments 0 comments Article is closed for comments.