Just to give you an idea, I conduct a lady's firearms safety and self defense class for two hours a week.
After a few of these classes its not problem for these girls, (most who have had no training prior to the class) can draw and fire in under 1 sec. We strive to get it to .5 sec.
Its not hard really, its more the method of carry.
It takes about 3 seconds for a bandit to kick in the door during a home invasion. 3 seconds to react is too slow in my opinion.
And yes a timer is a valuable tool.
Two drills I use:
The first requires you to get a blue training gun that matches your carry gun.
DO NOT USE A REAL GUN.
Have your training partner face you, close, less then arms length. Have him extend his arms body width apart, elbows touching side, palms open. He has his hands ready to slap together.
When he sees you start to draw, he is to slap his hands together. You job is to draw and get the plastic training gun between the hands before the come together, where your partner slaps the gun.
Sounds hard but with a bit of practice it really isn't.
Again, DO NOT USE A REAL GUN for this exercise.
2nd Drill:
Both you and your range partner face your targets (separate targets). Have your partner point at his target, ready to shoot.
When your partner sees you start to draw, he is to fire. Your goal is to draw and fire before he fires.
Again sounds impossible but with a bit of practice you can pull it off.
A huge majority of SD shooting is at bad breath distance. Speed is critical.
If you cant successfully complete the two drills above, then you need to re-evaluate your method of carry.