‘Umrah is mustahabb at any time in Ramadan
Question

Is ‘Umrah mustahabb during the last ten days of Ramadan?.
Praise be to Allah.The Prophet (peace and blessings of Allah be upon him) encouraged us to perform ‘Umrah in the month of Ramadan. Al-Bukhari (1782) and Muslim (1256) narrated that Ibn ‘Abbaas said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “ ‘Umrah in Ramadan is equivalent to Hajj.” 
This includes all of Ramadan, not just the last ten days. 
And Allah knows best.