Seedling questions, Please & TY

Well I'll introduce myself quickly,I have been in the canna field for roughly 11 years and have extensive knowledge. I've got 10s of thousands of beans. My buddy posted a Pic of his trichocereus tent and it intrigued me,I did some research and made up a decent sized note in my phone,here's my question,how long will seedlings survive like this,not being potted or in the ground? Question #2 I have loads of coco,but no perlite right now(be here in a week) should I wait till it comes and then mix it up 50/50 like I've learned to,or is it safer to just put them in coco now and then repot in a month or so with the 50/50 mix,seedlings from Team Wachuma😇 also I'm a genetics nerd that can't just put a name on something I have to know exactly what it is,that's why it's labeled like that,if you see something isn't right in my text please inform me cross wise so I know,I wont take any offense I'm here to learn and be a team member,much love everybody thanks for the help and input! Here's the other mix I was thinking about doing sense I do have warm castings. These will be in a tent setup,is my 650w led going to be to much on 20% at the roof? Or should I put them in my 2x2x2 with 4 t5 lights? Just curious. SOIL MIX 50% Coco,25% Perlite,25% warm castings.