Karthik R
Hi I'd stick to the formula shared in the post. And, the y value you are looking for the cell-centroid position (your first cell height would be twice this obtained value). The formulation takes into account the cell centroid height as we generally use the Finite Volume Method in CFD. If you are attempting to resolve the viscous sub-layer, your y+ value should be close to 1. If you intend to use the wall function approach, then you can have a larger y+ value (y+ ~ 30).
Hope this clarifies your question.