Let them germinate and form a little rootball first. This is how it is supposed to be done. If you put it immediately in the pot, there's no reason to use the plug. The size of pot and plant should jive together to avoid unecessary risks and difficulties in irrigation (pot being wet forever is no good.. easy to waterlog a tiny plant, unnecessary build up of nutes, etc...).
Big pot, small plant is a bad idea, even for autoflowers. It's a myth that you have to worry about transplant shock. What we do is not "transplanting". It is "up-potting," which is nearly impossible to shock the plant. you'd have to purposely molest the rootball and tear it apart, lol.. don't go all mongo (from blazing saddles) on it and you are fine.
You will avoid more problems by doing a standard up-potting process. there's no reason to add risks for urban myths.
I'm not sure how many i've done, but it's up around 300-500 at this point. Never seen shock from up-potting. I even erroneously tried to up-pot when the seedling substrate was too dry, and it nearly feel apart in my hand... just make sure there's enough moisture to hold itself together. You know what i do see often in questions? someone with a big pot, tiny plant and numerous issues because of the watering dynamic of that context - doesn't matter if it's an autoflower or a photoperiod.
You can read about other urban myths on cocoforcannabis.com. Between the guides and the posts in dr photon's corner, you can avoid a lot of bro-science and false common beliefs. The "to defoliate or not..." article is another must-read there.