Wearable finger-based haptics with cutaneous feedback is promising, as it allows us to duplicate many real-world rich/important tasks that are relying on the dexterity of fingers and hands in the virtual-world. For this system, one of the key challenges is the finger-tracking, which can of course never be perfect, yet, if used in VR (e.g., with HMD), would still be adequate as long as its tracking error is under a certain detection threshold. In this paper, for such wearable finger-based haptics in VR with HMD, via some suitably-designed human subject studies, we aim to quantitatively answer the following questions: 1) what is the detection threshold (i.e., just noticeable difference (JND)) of visual-proprioceptive conflict (i.e., error tolerance of the finger-tracking system in VR); and 2) is it possible to further reduce this visual-proprioceptive conflict by utilizing cutaneous haptic feedback. We believe these results would be useful to determine the design specification of finger-tracking systems for haptic and general VR applications alike.