Steven, this will depend on your level of skill developed from muscle memory. Always practice getting the firearm ready for firing at first hand contact so it is immediately ready to fire even before the target is acquired. Any time saved is critical time towards a successful engagement. This is whether it is a pocket, holster or anywhere else. Cheers and stay safe!

I dont pocket carry but I know people that have and they typically pocket carry with a quality pocket carry holster and either a gun with no safety or the safety off, as a good holster (regardless of how your carrying) will have a full trigger guard, which will keep you from dis discharging your weapon, as others have said get training, never touch the trigger until you have your target in your sights and are ready to shoot, know your target and what lies beyond it, dont point your muzzle at anything your not prepared to completely destroy.
To me a good holster is better the a safety any day, and dont have safetys on any of my pistols. Honestly if my rifles didnt come with safety's already installed I wouldn't have safeties on those either. Happy shooting.

Clear your pocket first. Shooting yourself in the leg is not a good thing. Get training.