Hola!
Sorry, we're in England, and trained Harry to go outside, so I probably can't help much
Are you at home during the day? Because, in or out, with any Littlie, consistency is the key. After all the 'normal' triggers (sleeping, eating, playing, 'circling' etc.) - onto the pad, and say "good wee-wee/poo-poo"
as they perform 
You will reach the point, hopefully in not too long a time, when he does it 'on command'.
When you're out - does Chewie have free roam of your place? If so, I
personally wouldn't allow that to happen - yet. Too much space and freedom = lots of mischief!
Some use ex-pens, others crates, others a safe gated area - bed, toys, food + water and lots of pee-pads!
Good luck! Sally + Harry
x