Seedlings

How long do they need to be covered coz my ones, i had to take the cover off em, coz 1 is growing faster than the other. I only planted them 6 days ago. Will they be ok with no cover over them cheers

just until the first tru leaves appear then take off dome

I had 2 take it off now because 1 was 2 tall, they got small leaves but not full. What will happen now coz the dome is off, will they survive