Going to run out of yarn (help!)

I started a knitting a jumper an embarrassingly long time ago (over 2 years ago). I've picked it up again and it's looking like I haven't got enough yarn. It's Dooish worsted weight yarn: https://www.skeinsisters.com.au/spinning-yarns-weaving-tales-dooish

Its looking like I'm going to need to buy an additional skein years after the initial lot. I'm hoping for some advice for how to best join a new ball from a new batch number without a glaringly obvious line due to a slightly different colour. I'm knitting neck down on circular needles, and am halfway down the body. Would starting the arms in the new ball look fine?

Help a scared novice knitter out please!