In Jain practice, the previous day’s last meal should be finished before sunset. After sunset, eating is avoided.

If you mean Navkarsi time in the morning, it is generally taken 48 minutes after sunrise.

So, in simple words:

• Stop eating the previous day: before sunset
• Take Navkarsi the next day: 48 minutes after sunrise

If you want, I can also explain the difference between Navkarsi, Porshi, and Sadhporshi.