Its not fun, and if you dont have the will power to taper off your opiate of choice and then wait 24 hours (or more depending on the opiate your using, you will end up with percipitated withdrawals, which are much worse than the first two days of
cold turkey withdrawal from heroin. Its pretty much an instant jolt from feeling ok, or bearable, to suddenly feeling anxious, jittery, throwing up, and generally worse than you did had you just tried cold turkey without.