By the time I got round to doing a digi I was 2-3w.
I dont think Id rush out and get one though, they arent super sensitive and even FRERS say despite being able to tell from 6 days before chances of getting a positive decrease the earlier you test.
I think earliest Id do a digi would be date of missed af. Before that Id do a FRER or superdrug sensitive.
Also, when do you think you may have implanted? Some dont implant until 10dpo so, in order for it to work youd have needed to implant super early for the hcg time to build at 8dpo.
Good luck.
xxxx