Vivaro B 1.6 90 hp starts badly

Hello people, after an ad-blue problem, which was solved by cheerful parts exchange, I am no longer particularly positive to talk to Opel workshops. Therefore, I would like to discuss a problem here first and hope for really knowledgeable members. My Vivaro B year 2017, 1.6l 90 hp with now approx. 140t km starts badly. I bought it used and really well jumped it has never except in warm condition. Sometimes I already had the feeling that it at kal I can’t define it correctly, only sometimes I’m surprised that it starts the first time. In a cold state it’s common to start twice and even the second time it can still be that you have to “org” for a short time. The glow candles were changed about 10t km ago. My thinking is, that the temperature of the outside is even slightly lighter, like when it was very summer temperatures, when it was in the sun all day long. the glow plugs may not really glow, so they are not controlled at all. Could that be and what would be the cause? Is the control unit responsible for this and where does the control unit get the information to pre-glow? Is it pre-glowed during each start process (i.e. also in a warm state)? Or is there completely different reasons? The compression has not been tested so far, but in my opinion the engine of the power should be in order. kstatt be tested and could this also be done by a free workshop (without Opel software or tester)? Greetings to all Colo