How long till I can test?

Shayla • Mommy to 2 angels 👼 •Mommy to Myah 🌈 👑 👶 Divorced once. Happy Again 👨‍👩‍👧

I miscarried on January 4 and doctor said I can get pregnant right away. My HCG levels were at 0. I have not had a period yet. When can I test for this next pregnancy?