Flying in a sim before actual training can be beneficial - however theres a couple of things you need to bear in mind:
1. Flying a basic trainer in real llife is very different to flying in a simulator. The technique that you use in a sim won't work in the plane - listen to what your instructor tells you and follow it! I've had issues with sim students previously who spend way too much time looking inside at instruments in a VFR trainer because "its the propper way to fly"... it isn't.
2. Forget IFR procedures for a while, being able to follow a NAVAID will be beneficial eventually... but it won't help you read a map.
3. "But in the sim" won't fly with an instructor... they're telling you things you need to hear/follow - Don't discount that information because "but in the sim", you'll be wasting your money and their time.