The OED Online entry ("not yet fully updated...first published 1911") for "teetotal, adj. and n." provides a lengthy etymological note. Some points made in that note remain good; other points can be contradicted with evidence now available from online reproductions of historical newspapers and journals.
Etymology: A kind of emphasizing reduplication or extension of the word total adj. and n.
The most specific account of this word is that it was first used (in sense A. 1 [Of or pertaining to total abstinence from alcoholic drinks; pledged to, or devoted to the furtherance of, total abstinence]) by a working-man, Richard Turner of Preston, about September, 1833....
["teetotal, adj. and n.". OED Online. December 2016. Oxford University Press. http://www.oed.com/view/Entry/198589?rskey=evqZhH&result=1&isAdvanced=true (accessed January 12, 2017).]
That 'teetotal' is formed as an "emphasizing reduplication" remains true. That "it was first used (in sense A. 1)...by a working man etc.", while it may not be true, was not contradicted by any of the contemporary evidence I examined.
...It has been suggested that Turner only used a word colloquially current in Lancashire in the general sense A. 2 [dial. Absolute, complete, perfect, entire. (More emphatic than total.) Cf. teetotally adv.1. But to this the whole tenor of contemporary evidence is opposed: and the examples of tee-total in sense A. 2 in Eng. Dial. Dict. are all of much later date.
The evidence I examined did strongly suggest that "Turner only used a word colloquially current in Lancashire", notwithstanding that attestation of tee-total in EDD is all from later than 1833. Even supposing it is not agreed that the now-contemporary evidence (presented next) strongly suggests "Turner only used a word colloquially current", the evidence now flatly contradicts what was undoubtedly true when published, that "the whole tenor of contemporary evidence is opposed" to the notion that Turner used a current colloquialism.
The evidence suggesting that Turner used a current colloquialism includes uses of 'tee-totally' in newspapers (behind paywall) from Cheshire, England (1810), and Waterford (1828), Dublin, Limerick, Newry and Cork, Ireland (1832), as well as use of 'tee-total' in a newsletter from Dublin (1832):
Chester Chronicle (Cheshire, England), 07 September 1810.
Waterford Chronicle (Waterford, Ireland), 23 February 1828.
Dublin Evening Post, 27 November 1832. This article was also reprinted in the Newry Telegraph, 30 Nov 1832, and the Cork Constitution, 01 Dec 1832.
Limerick Evening Post, 30 November 1832.
Saunders's News-Letter, Dublin, 17 September 1832.
It is evident from these uses that 'tee-total' and 'tee-totally' were colloquialisms in relatively common use, especially among the Irish, from 1810-1832. 'Tee-totally' particularly was likely to have been known to Turner before his September 1833 speech, as a result of the word having been widely disseminated in the article detailing the proceedings of the Irish Trades' Political Union, 25 Nov 1832, a scant ten months earlier.
Note that OED attests 'tee-total' in the dialectal sense of "absolute, complete, perfect, entire" (A. 2) from 1840. The early use shown in the foregoing was not known to the OED lexicographers in 1911. 'Tee-totally' in the sense of "Totally, entirely, wholly" is attested from 1832 in OED, but in the US, as this from the lengthy 'tee-total' etymological note observes:
...there is proof that the adverb tee-totally, as an emphasized form of totally, was used in U.S. in 1832, and it has also been said to have been common in Ireland from a much earlier date. Totally is much more frequent in colloquial use than total, and it is quite possible that it was strengthened to tee-totally much earlier, and that tee-total in the specific sense arose independently, and without any knowledge of the adverb.
As shown by the clippings above, there is now proof that 'tee-totally' was used in Cheshire, England, as early as 1810. Preston, Turner's hometown in Lancashire, is a mere 44 m. (72 km) from Cheshire.