My first ever grow

Thanks for taking a look at my first ever grow. I have noticed a couple yellow spots, think the light may be a tad close. Trying to keep it between 4-5 inches above the plants. Temp seems very high during the day, 34. I’m using T5 lights, model MK3 PL4. My plan is to repot them at 4 weeks, ready to switch to 12/12 on the lights. I’ve been advised to slowly change from 18 hours to 12 hours, hourly at a time over a week. I’ve only got space for 8 plants in the tent, I’m using 2 600w HPS lights, with the plants being put in 12 litre pots. As it’s my first grow I’ve decided against LST of any kind. Any advise, or simply telling my I’ve got something wrong would be really appreciated. I’m just going off what I’ve found online. Thanks.