The Futaba 12FG motor menu gives you several options to play with. I have highlighted in the respective colour what does what.
The first part of the ramp is called SPEED 1 and the second half is called SPEED 2. The number ranges from 0 to 27 where 27 is really slow and 0 is instantanious. Sensible numbers are between 10 and 24. I always use 10 for speed 1 and something around 22 for speed 2.
Then there is the switchover point. This is called (SPEED 1 > 2 ) and can be adjust from -100 to +100. Sensible numbers are around -25 to +10 and you should adjust in steps of 5 or 10% at a time.
Note that there is an IN and OUT speed given. You want to add a delay on the ON side only and not when switching OFF the motor.
Note that in some cases things may be reversed, it may also depend on if you use a throttle stick or a switch. Try the manual for the TX you have and/or experiment a little with a servo plugged into the throttle channel.
Page 103 of the 12FG manual reads MOTOR;