The earliest possible dating of any uncanonical Gospel is perhaps 150 AD in the case of the Gospel of Thomas, but apart from that text and the Protevangelium of James, no uncanonical text can be realistically dated earlier than 250 AD - their writers were born more than a century after the last possible eyewitness had died.
Also, these texts are often portrayed as having been contenders for inclusion in the Bible with equal standing to the canonical texts until they were eliminated from the running for presumably "political" reasons. In reality, the canon was pretty much closed and set by universal consensus in the Church before these text s were even written. Most of the texts bear the mark of theological fashions that were really popular and trendy among pagans in the 200s but which would have been completely unfamiliar to Jews writing before 100 - which is what these forgeries claim to be.
Point of reference on dating:
Did you know that the koran was compiled 200 years (at least) after Mo died? From scraps of scrolls, wall scribblings, and tapistries - all of which the original authors were unknown.