Last year (2015) dates of events

psychometric test : 24 Jan ,2016
Result : 2 march , 2016
Interview call letters issued: 28 march 2016
Interview started : 7th April
SVA forms issued : 30 June 2016
Last date to submit SVA forms : 14 July 2016
Medical/Joining call letters issued : 23 Oct , 2016
Training started : 01 Nov, 2016

From above dates u may get the idea of approximate time u may have to wait between different stages of this test