You need an Omron H3Y timer, 12V, 60 second (or whatever range fits with the delay you want).
https://www.lazada.co.th/products/1pcs-h3y-4-dc-12v-delay-timer-time-relay-switch-0-60-minuteseconds-adjustable-5a-with-base-socket-rotary-knob-dpdt-i4421023836-s17670357090.html?
Other sources may be cheaper, or your local electrical emporium may have something suitable.