Pregnant?

Had my implant removed 2 weeks ago... Had a period about 3 weeks before I had it removed. But was due on roughly 4 days ago and I haven't come on yet I'm late. Do I need a period after having the implant before I can get pregnant or could I already be pregnant? I already took a test few days ago but it was negative. Obviously because it was too soon?? When's best to do a test? A month later? Few months later? Xx