I've had one pregnancy and one child, and it was as immediate. I got off birth control, had my period, timed when I thought I'd be ovulating, and was pregnant when I tested two or three weeks after ovulation.
I expected to have problems because my periods we're always so painful it required days of school, visits to the nurse/doctor etc. Extreme pain like that makes me throw up, I couldn't eat or drink anything every month for the first two days of my period. I would throw up water too- hence I couldn't go to school and usually ended up at the doctors office for dehydration.
My doctor eventually put me on the pill to ease my symptoms and I thought because I went on the pill at such a young age, I'd have problems.
There were no problems, so there's hope. Good luck. xox