How soon can early pregnancy spotting happen?

My period came 4 days early and i had a week of spotting.

I use a cup and everyday just had the tiniest amount of drops that you couldnt even see once id throw it in the toilet

Ive never had such a light period before and Ive been having unprotected sex.

Could this have been early pregnancy spotting?

I feel like id tell anyone else it was their period but it was just SO light it has me wondering. Ive also been eating like a mad woman, tired, and have had lower back pain, but i feel like maybe thats just all coincidence as it would still be early.

Does early pregnancy spotting occur as soon as first month or does that happen later on?

Thanks