mixing seedling of different ages

I just got my seeds in the mail. about 2 weeks ago my friend gave me 2 free seeds so i germinated them and they are approx 12 days old. Is there any problem that would occour if i germinated the seeds i got and grew them all together even though 2 are 12 days ahead of the rest?

Nah. They might be shorter. Might be. If the seeds he gave you are sativa dominant. The seeds you got are indica dominant. The sativa will be taller even with the 12 day spread.

If they're close in finished height. Imo, you might see a 3" difference in plant height.

just don't forget to add an ID stick

include the date of germing and the name

good luck