Would make 10,000 years more or less ... and as an immortal he has spent them awake most probably.
Thinking about it ... does he remember his parents at all? More than a very vague "childhood" memory? When they meet again in TFQ ... how will they interact? Will they be familiar at all? Even Dewshine has problems to remember Windkin's young adult days ... and it is only 500+ years for her.