For anyone playing around with CLTV transaction using "regtest" you should note that you will likely need to generate multiple blocks between sending funds to the the P2SH script address with the future nLockTime and when you want issue the tx to spend those funds due to the handling of the nBlockTime being based upon an average of the last X blocks.
https://github.com/bitcoin/bips/blob/master/bip-0113.mediawikiFrustrated me for a day so if you're getting the non-final errors when you think you shouldn't just try a "generate 10" and repeat.
