at once
directly
forthwith
immediately
in a flash
in a jiff
in a jiffy
in a twink
in a twinkling
in no time
in nothing flat
in short order
instanter
instantly
just now
just then
momentaneously
momentarily
momently
on the dot
on the instant
on the nail
on the spot
outright
promptly
pronto
right now
tout de suite
without delay