Ideally to get the best results we need your sample as quickly as possible especially in warmer weather. Bear this in mind when you are posting back your sample as delays in the post could affect your results. We suggest you collect your sample on the morning of posting and return to us Monday to Thursday that way it will not be delayed with Royal Mail over the weekend. Remember to avoid Bank Holidays also! The Freepost return label we supply is 1st class post to ensure your sample reaches us as quickly as possible.