Mel, definitely yes. Jack did the same thing. He was actually night trained before being fully day trained. He started wetting his nappy only once every few nights, and then we'd sit him on the toilet before putting another nappy or undies on him in the morning. After a while he asked to wear undies to bed. He still wasn't dry every night, but I took the chance that it was because he had the nappy on and could wee. It seemed to work, he wet a few times but not often, and with a waterproof matress cover it was no big deal. Of course by this stage he was semi-day trained, so you are probably not up to undies at night yet, but I would definitely be starting to TT, and sitting him on the toilet or potty for his morning wee would be a good start.

Just bear in mind that he will probably regress when bub arrives, so take a softly-softly approach and maybe get into more concentrated TT in a few months when things have settled down.