Question: Is it true that Witr prayer must be finished at least 10-12 minutes before Fajr time enters?
Answer:
In the Name of Allah, the Most Merciful and Compassionate
The Witr prayer is valid if performed anytime between the performance of ‘Isha and the entering of the Fajr prayer [Tahtawi/Shurunbulali, Hashiyat Maraqi al-Falah].
There is no stipulation that the Witr prayer must be complete 10 minutes before the Fajr prayer. Your prayers are thus valid and do not require repeating.
Hope this helps.
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani