Beginning March 16, 2015, a visa must be issued within 90 days of receipt of an approved 212(d)(3)(A) waiver. INA 212(d)(3)(A) waivers are valid for the duration indicated by the ARO officer in the ARIS response. The waiver validity starts on the visa issuance date.(Source 9 FAM 40.301 N8)
See more at DOS website: http://www.state.gov/documents/organization/87150.pdf