Maybe I need to clarify. My point is simply that it's rather silly and pointless to debate whether the NT authors meant cross or stake. While I personally believe many of the texts themselves strongly indicate 'cross' and the arguments of the WT for 'stake' are inaccurate at best, I wouldn't try to argue for the use of a cross because of a timeline, seeing as the timelines differ.
Further I'm kind of leaning toward the hypothesis that the earliest layers of Christianity saw the merging of a heavenly 'son of man/son of God' cult with any number of historical personages such as the teacher of righteousness from Qumran. Paul seems to represent an intermediate stage. A few decades later in Rome the anonymous work later named the Gospel of Mark appears to be one of the earliest narrative tales stringing together OT typological elements in Midrashic style to create a new story depicting this new hybrid character engaging in miracles, fulfilling "prophecies" and exposing the established religious order as corrupt. To write that narrative the author naturally drew from the idiom and motifs of the literature of Homer.
In line with that reconstruction, I find the Wells, Doherty proposals persuasive. One of the most difficult aspects of Doherty's hypothesis is why the earliest Christians might have envisioned a Christ being 'crucified' by spirits upon a cross in a lower heaven. In my estimation a tree represents a much easier proposal. Much like the Ascension of Isaiah reads:
14 And the god of that world will stretch out [his hand against the Son], and they will lay their hands upon him and hang him upon a tree, not knowing who he is.