Hey, @rikcote, welcome to ILGM! That fixture should do really well for seedlings, and through at least part of the veg stage, since 6500K will lean more toward the blue end of the spectrum. It won’t give you the greatest penetration once the plants start getting a little taller, but the color temperature should keep them squatty to begin with. You can raise it away from them at the loss of some penetration and intensity, if you need them to stretch a little for training or anything like that. But you should be able to start with them right down on the seedlings, within 6-8" or so once they’ve sprouted.
You may have pests to deal with outdoors. You have more control over pests as well as the environment indoors. Timing is key, but if the weather is right, as long as there’s no frost, it might not matter so much. I’ve never grown cannabis outdoors, but if that’s an option, sun is free! My outdoor inexperience stated, I’d start them indoors under your T5 fixture, in either the big solo cups, or pots about 1 quart/liter or so. Then when they’re established and ready to pot up, I’d transplant them right out into the ground, amended of course, or into some 7 or 10 gallon cloth pots. But you’d be watering more often with the cloth pots. I’ve also never grown autos. @blackthumbbetty and @HornHead both grow autos and can probably add better advice for them. I just know that outdoors in the sun, with room for roots to spread out, you’d have a much larger yield than indoors.
Excitement is good, but make sure you do your research and make good investments the first time. There are tons of experienced, knowledgeable growers on here, and there’s no such thing as a dumb question.