When to test?!

Kristin • Expecting #1 in December. Our greatest gift from God after mc last oct. So thrilled
Im trying to figure out when to take prego test. I got a positive opk oct 5-6 af due thurs 10/16 so I'm about 7-8 dpo.
​I have been cramping and back pains. I want to test but is it too soon? Don't want to also test too soon
​Any advice? Please please