Lay your table on top of the pedestal (may need an extra hand with this)
Line the 3/8" hole of the table to the 3/8" hole to the pedestal. Use a 3/8" bolt and tighten them together.You will have to go through the 15" diameter hole on the bottom of the pedestal that you made in step 2
Now drill 4 more 3/8" holes through the center of the table through the cap of the pedestal and countersink them. Use 3/8" bolts to tighten the table down to the pedestal. This will prevent the table from rotating on the pedestal. (Be sure the heads of all the bolts are flush with the MDF so the playing table sits flat)
Use more trim to cover up the bottom and top pieces of your pedestal to hide any nails you used to assemble it. Also use trim with 3/4" radius along the edges of the octagon base of the pedestal to cover up the thickness of the plywood you used.
The trim will add a unique look to your table and make it very pleasing to the eye.