I would go with what works for now, I am sure they say they don't form habits till approx 3 months and habits are always easier to break when they are so little anyway. I know how miserable I can feel with a cold so I am sure little ones feel so much worse (except for a man with man flu of course

) and so doing anything that makes them feel better would be the way I would go.
My DD is nearly 10 months old and has just had her first cold and then another almost straight afterwards (I had it at the same time as well). I went with whatever kept her happy and comfortable. One thing I found really helped was a vapouriser & once we could no longer borrow that we used a crockpot with the lid off and a bit of vicks in it, don't know if this is okay for such a young baby but worked wonders for DD's breathing at night.
Hope she gets better soon and you do too.