90 days from today is Sat, 20 April 2019
Provisions relating to pay can be found in Regulation 24 and Annex F of Police Regulations 2003.
Pay is usually uprated annually from 1 September.
JBB Circular 39/2015 notes that an agreement was reached in December 2015 with regards to the calculation of holiday pay. It details that officers are entitled to holiday pay that includes their regular overtime pay and several other regular payments.