There are some perks to pre-ordering - you’ll get one of the first units available and bundled alongside will be the new Gear VR headset with motion controller.
Still, it may be prudent to wait for the first reviews to come out, the Galaxy S8 duo will not ship out until late April so there is plenty of time to think and still grab that free headset.
Others may want to wait even longer - especially those who think the S8 is too expensive. In a few months we should be seeing new phones from Xiaomi (Mi 6, perhaps a Mi Mix sequel), OnePlus and even the Galaxy Note8. Father of Android Andy Rubin has something special in store as well.
The “wait and see” game may lose you the VR headset (or not, it’s a common promotion), but it will help you make an informed decision.
Of course, there are several flagships that were made official but are not available in stores yet - the LG G6, Sony Xperia XZ Premium, Huawei P10 Plus and others. Did you pick one of those? Or do you belong in one of the other groups?