Smoking Diesel

I drive a 2014 Ford Fiesta 1.5 TDCi Zetec and have it serviced yearly. My service is next due only in October and over this cold spell it is smoking badly every time I accelerate / pull off. I can see a puff of smoke from my review mirror and have noticed it sometimes when I change up a gear. Other than that the car is behaving normally, no other issues. I have only noticed this over the last two weeks while its so cold so unsure if it is just the cold or another issue. Do I need to get it looked at or is it ok to wait a few months until closer to my service due date?

Marta - CR0

Asked: February 28 2018