Allen, 22, tore a hamstring after scoring a try hat-trick while winning his fourth Wales cap in their 2015 World Cup win over Uruguay in September.
He could face Newport Gwent Dragons at Rodney Parade on Sunday, 27 December.
Failing that Allen would be back on New Years Day when Blues host Scarlets in the Welsh capital.
A successful return would give Allen the chance to press claims for a Wales spot in the 2016 Six Nations.
Cardiff Blues expect Wales centre Cory Allen to return from injury during their festive Pro12 Welsh derbies.