When should I return a sample?

Please return your sample the same day it was taken. 

In the UK? Pop your sample  in the prepaid envelope (no need to get a stamp) and post it back on using any Royal Mail post box in the UK. You can also find a priority post box here: https://www.royalmail.com/services-near-you#/

What do I do if Day 3 of my cycle falls on a weekend?

Saturday - Please collect your sample and pop it in a post box with a Saturday collection. 

Sunday - Please still go ahead and collect your sample, close the lid securely and keep it at room temperature and out of direct sunlight. Please post it first thing on Monday. If you are posting from Ireland, please schedule your collection via DHL for the earliest available pick-up slot.