Regulating after birth control

Katryce
How long did it take your body to regulate your cycle after coming off of birthcontrol.? Currently on cycle day 26, a month off of nexplanon (had 16 day cycles before, i know thats short and this month im regulating). Im ttc, and was was planning on using opks. But im not wasting them on irregular cycles. When should i start really using them.?