Kench jungle should be easy street. Start q and get a leash on blue buff and kill it without using smite for the best clear. Level w at 2, then smite-devour gromp, which will nearly kill it instantly. After that, you should have a very simple clear. Max w first.
You can go two routes with Tahm jg: devourer or cinderhulk. Devourer is ridiculously strong on tk jungle because you do tons of on hit damage with your ult and, more importantly, you stack your passive much faster. Rush titanic hydra after devourer so that you get the nice aa reset to instantly stack your passive, plus its passive synergies exceptionally well with your own.