I think it's not a bad strategy. As you said you are doing no marketing and won't probably get featured by Apple. By being paid first you'll see how is the game doing and at least have a backup plan (by changing it to free). I also think that having a paid game is an advantage these days full of crappy high-IAP ripoffs. Some players still prefer it..
But when you decide to switch to free it's essential to use an App Discovery service. We are actually such a service and we offer the promotion completely free of charge (but hurry up - only limited amount of spots!) So don't hesitate to contact me! Please check https://appdown.me/front/developers