Wrong direction mang.
If your casually dating and openly non monogamous what you describe will work. But if your looking to get a girlfriend that will blow it up pretty fast.
Girls love a bit of competition. They want what other girls want, they love to brag about their man to their friends. For girlfriend material, you want to appear to have lots of choice and options - but make them feel special because you are sticking with them and not running about chasing tail.
Often you dont need to even be talking to any other girls to foster this competition. Just blow their mind on and between dates and make them feel like you could pick up any girl by treating them the way you are treating her. Be very gentlemanly (but not flirty) to waitresses. Be very gentlemanly to her around other girls (they will comment, beleive me, i have had waitresses compliment on my fine chivalrous manners to girls ive been on a date with). Thats enough to get the job done.
Key is to not be needy and clingy once you go exclusive. Be slighly unavailable and at times a bit noncommital about making plans with them. Wait for them to text or call you first sometimes, if they trip and wonder whats wrong just say you thought that they were busy or wanted space.
Getting clingy and desperate for her attention is he number one trap for dudes when a girl you go exclusive with your really into. If you do this you will flip from hot confident alpha or beta to needy pathetic gamma overnight and she will find the transition awkward and weird.
If you cant do this without talking to other chicks leading them on then you need to date more forget the girlfriend your not ready.