More brass, therefore more heat-sink, takes more time to heat up and vapourise the alcohol. Agree the first thing to do is to clean the jets. Bear in mind that this part was designed to go inside either the Meta-50 or the SAT, and in this configuration reflected heat from the metal around it (and the windshield effect) speeds up the bloom time considerably.
Lastly, for some reason or other, the "experts" on youtube etc all wait for the jets to bloom before putting on the relevant pans. In fact, as soon as the central part lights, stick on the pan and the reflected heat from the bottom of the pan will speed up bloom. THe Meta-50 is insulated from the floor by the set-up. On the SAT, the army trangia sits on the ground. Try to insulate this from the ground in cold weather, as otherwise the ground will leach heat from the burner, delaying the bloom. For lighting in very cold weather, stick a wick of some sort (even a twist of tissue paper will do) into the centre of the burner, and light that.
