1)If you want to go for a m20,which is generally a good idea against okw,then you have to ensure that u can field it is as fast as possible.Start capping the points next to your base,to have a constant supply of fuel at the beginnning.
2)OKW has a slight advantage against any faction for the first 4-5 minutes,keep that in mind.Play more cautious until your LT,m20 hits the field.
3)Capping order,dont cap points that arent connected unless it is a VP.Mainly cap with REs.
4)M20 should constantly be harrassing his cut off or defending yours.He capped your fuel while your m20 was just sitting around the center,waiting for anything.
5)Why did u get grenades in the first place ? If you saw his loadout (3x Shrecks) then you should have gone for bars to overwhelm his infantry.The commander choice was good,so you might be asking why lmgs instead of bars ? They are better while moving and excel at mid-close range combat.
If you have any further questions pls ask