u/EK0-44

Recently bought this 320D E92 with the N47(chain was just done 294,000km with receipts) some mornings it takes a second or two longer to crank over but sometimes I get this blueish smoke only on start ups while it heats up, I know I need to replace two glow plugs but is this something more underlying that could be worse, any and all advice welcome I need to learn more. This is my first Turbocharger diesel, I went from a 1.25l petrol to a 2.0L diesel, I know absolutely muck all.