Tell your partner right away, do a test to find out, or wait for your period and see.
For context we are not trying to get pregnant.
I have had some bloody discharge today (v small amount) but my period isn’t due for 4 days. I know it could be an early period so on the one hand seems silly to worry him about it just now, and also seems silly to test when I could just wait 4-5 days and find out either way.
But on the other hand I feel like I’m keeping something from him if I know for multiple days before I say anything.