In the equivalent circuit of transformer is the shut branch placed before or after the winding impedances in the primary?
The "shunt" branch (as I believe you are referring to) represents, amongst other things, the magnetization impedance as depicted by the impedance \$X_M\$ as shown below.



That branch is sometimes (in books etc.) shown across the far left terminals and this makes it easier to do the math when dealing with problems. However, there is a sacrifice made in doing so because it then doesn't fully represent the leakages (typified by \$X_P\$ etc.) and can lead to some errors.

My preference is to leave it exactly where it should be as indicated above.