Blood test Thursday

I am waiting for my blood test on Thursday to see if the round of IVF worked. I have taken tests, but promised I wasn't going to do them and ended up caving in the afternoon. All three came up negative. I am trying to be positive since the last time I got a BFP I tested a week after my missed period and got a very faint line. With this whole procedure through in off my cycle I don't know when it would actually come. Can it take longer to implant in some than others?