>>..surprised to see that Oxford English Dictionary (OED) do not acknowledge the usage.
>..am pretty certain that prepone is in the OED.
this piqued my curiosity of course, so I peeked. prepone is not in OED2, but it's going to be in the new B&M edition; here's the Sept. 2001 draft entry:
1. trans.To place in front of; to set before. Obs. rare.
1549 R. CROWLEY in Psalter of David XVI. sig.C.iv.v, I do prepone and set the Lord alwaye before myne eyes: He is styll at my right hande, leaste I fall in anye wyse. 1625 A. GARDYNE Characters & Ess. Ep. Ded. 5, I stood, and studi'd, whose pręponed Name Should dye in Graine, and Luster lend to Them.
2. trans. To bring forward to an earlier time or date. Opposed to postpone.
In later use, most frequent in Indian English.
1941 M. KELLEY This Great Argument iv. 105 He [sc. Milton] preponed to a period before the foundation of the world certain dogmatic matters connected with the accession of Christ to the mediatorial office of king. 1978 Church Times 13 Oct. 8/5 Longman would like to announce that the publication date for Linelights has been preponed (brought forward) from 16th October to 25th September. 1987 Summary of World Broadcasts: Far East (B.B.C.) 14 Oct. 8698/B2 The winter session of Indian parliament, which is normally convened in the third week of November, has been preponed to early next month. 1997 Independent 26 July I. 15/3 On my recent visit to Delhi, I was handed a note by my client's driver who met me... The note stated that my meeting with my client had been preponed. 2001 Times of India (Nexis) 22 Feb., [The] transport minister..decided to ask schools to prepone their examinations and start summer vacations in April in view of a transport crisis. [OED online]
(EA)
