Possible BFP even though AF come early!

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Hi, I started my AF today I believe (1 day early). But I am so emotional it's unbelievable at the moment. 
In the last 2WW I've had sore breasts and felt nausea a few times. Is there a possibility I could still get a BFP? I haven't tested this month, but think maybe I should. Should I wait till after AF has finished or do it straight away?