I've been doing a lot of research lately and the earliest Githens I've found is John Githens b. 1720. Despite many trees showing him born in NJ I haven't actually found any documentation to prove it.
What I have found is a mention of a Philip, John and Mary Githins (note the spelling, I have also seen it as Gittins) in the will of a Mary Hoskins (maiden name Githins) dated 30 Jul 1678. The 3 mentioned above were the children of her brother who had already died in Maryland (in the will it's spelled "Meriland").
There are also immigartion records showing a John Githins arrived in Maryland sometime in 1678 and another showing a John Githins arriving (I think) in Barbados in 1679.
My Theory is the John Githins mentioned in the will is the father of John Githens born in 1720. However I have absolutely nothing to back that up.
Do you have any info on a Githens descendant before 1720?