Peat pellets or tray with dirt?

Im planting 300 plants tommorow coming out of germination and im wondering what would be best acouple trays with pellets 72 spots per tray or the same trays take away the pellets and just add dirt i dont have time to start all in red solo cups this year and let get to the size i want before transplanting to the ground so i have to go with this tray method probably gonna let grow acouple inches tall bringing them in and outside everynight before i bring them to there pernament home for the summer also would anyone reccomend using a rooting gel when theyre still that small at transplant time or whats my best bet? and ive seen certain planting orders inside theese trays in certain lines or diagonally and wondering if its safe to put 72 plants in one tray or maybe just fill the tray halfway each spot is its own little whole so the roots wont be getting all tangled up thanks for your help!

i would think pellets would be better less stress when replanted.