When your seedlings all have at least 2 sets of true leaves and are ready to pot up and be given to friends, put each one in an 8 oz styrofoam coffee cup with a couple holes punched in the bottom with a pencil. Styrofoam coffee cups are endlessly reusable for plants as long as you don’t crack it, and you can write the name on the outside with Sharpie.
If the MG potting soil says “feeds for 3 months”, then you can start adding some half-strength fertilizer after about a month. It’s a really tiny amount of fert that they include, it’s mostly just there to look good on the label.
Always cut potting soil with about 1/4 to 1/3 of some kind of lightener such as perlite or vermiculite. Used straight out of the bag, it tends to be very dense, moisture-retentive, and slow-draining.
Sometimes those modular plastic pots, with the attached saucer, will actually allow you to snap off the saucer. You have to kind of work with it, prying it with a screwdriver, but they do frequently come off.
I did manage to get the bottom of the pot off. I will try watering from the bottom as recommended here, using the 2 knuckle method. Note also that it should be watered from the top once a month to rinse down salts and things.