Synonyms of in a jiffy in English:

very soon, soon, in a second, in a minute, in a moment, in a trice, in a flash, shortly, directly, any second, any minute, any minute now, in a short time, in an instant, in the twinkling of an eye, in no time, in no time at all, in less than no time, before you know it, before long

North American momentarily

informal in a sec, in a nanosecond, in a jif, in two shakes, in two shakes of a lamb's tail, before you can say Jack Robinson, in the blink of an eye, in a blink, in the wink of an eye, in a wink, before you can say knife

British informal in a tick, in two ticks, in a mo

North American informal in a snap, in jig time

archaic anon