If you use an ovulation test, you’ll know when you see an LH surge that you’ll ovulate within the next 24 to 36 hours. This means you will enter the luteal phase in around 24 to 36 hours. Alternatively, if you are tracking your BBT, when your BBT increases it’s an indication that you’ve already ovulated and are entering the luteal phase.
The luteal phase lasts from ovulation to the day before your period starts.