I did the same for mine (except wooden stock) - about 3" back from the gas block. I oriented the bi-pod adapter for the stud (in the picture) so the two slots were forward of the stud. I have since swapped it around so that the two slots are rearward of the stud. Makes for a nicer (IMHO) stance and in about the same place one would have naturally placed the rifle were one using a rest.
I would caution that putting the stud into the stock without a threaded back plate to secure it will likely cause it to fail. As little felt recoil as there is, there is enough to strip the thread and have it come out. I started out using a coarse-thread stud into my stock and all felt great and solid. Until after firing, when the stud (and bi-pod) was very loose and had started cracking the stock. So I bought a T-nut at True Value, enlarged the hole a little, shaved off two sides of the T-nut base (so it resembled a rectangle rather than a circle) and used a machine-threaded stud. Made it much stronger and I no longer am concerned about it working loose or cracking the stock more. I even used a small washer between the stud and the wood stock to spread out the pressure.
There are several threads on this forum about how to do this. Harris also makes a kit that - while not specifically designed for the Mini - works with some minor fitment.
Key to all of this, of course, is making sure nothing impedes the op-rod cycling.
Very nice looking Mini you have there!