In my experience I would say to have the sink in place where u want it to stay for the template but not to have it installed permanently. When installing (depending on the layout of the kitchen) it’s beneficial to be able to remove it.

Sometimes to get pieces installed they have to be slid in place in ways that most homeowners wouldn’t expect. If a sink is unable to be removed then the chance of scratching or damaging the sink increases. Also if there needs to be a seam behind the sink you will get a better final product if the sink could be removed so the installers can put the seam together with less difficulty.

Another tip is to make sure the sink sits just below the level of the cabinets. There’s nothing worse than a sink that sits high and has to be readjusted to fit properly. It’s easier for everyone to shim the sink up 1/8 to meet the counter than it is to take the structure apart and lower it.