might find this helpful,
In San Diego, Dr. Bastuba has successfully reversed patients up to 30 years following vasectomy with pregnancy occurring as early as a few months post-op. http://www.malefertility.md/vasectomy-reversal .html
it depends on the type of vasectomy and the length of time between the vasectomy and the reversal, but it is possible to get pregnant that soon, though usually it can take 4-6 months