dep shot and sex

Dalalalsh
So I gave birth on Nov. 18, 2016 and got the Depo shot on Feb. 15th with no period. 
Not sure when it start its effectiveness? Some websites say 24 hours if taken on the 5th day of your period and some say use condoms on the first 7 days.
And we had sex after 24 hours and now I'm freaking out 😭.
Any help?I