Same for me. I posted the test on Wednesday afternoon and tracked its delivery. It arrived at lab on Wednesday night. I then did not get my test result till Sunday morning. It was a long time to wait, and I was convinced that something had gone wrong, so I went along to a test site on Saturday afternoon (3pm). I received result from that test the next day at 5pm. I recommend everyone go to a test site rather than use the at home kit. Test site was completely empty, and I was able to book a time straight away. Quick result was worth effort to travel (had to walk as not allowed public transport and no car!)
