When to start feeding?

I have 10 plants going. All about a week or so old. In some nice Pro-mix soil. When should I start feeding them? I have some 20-20-20 i'm going to apply but start with very small doses so I dont burn them.

Heres some pics of them. Advice on when to feed please!!

if you can try to get something with a higher nitrogen amount and less PK. promix doesnt have nutes so plants need to be fed sooner in it than say fox farm ocean forest but your plants are too small for nutes now. i would wait 4-6 days before feeding them

What would you recommend me using? I always used a 20-20-20 in the past with decent results during flower I use a 10-54-10. Wait about another week before I start to apply fert? I'm not going to give them entire dose I plan on feeding them a small amount and gradually work my way up to full feeding.

you will get mixed answers to this but pe4rsonally ... I dont feed anything untill I see the first true set of leaves and then start very lighly ...only feeding everyother watering. Then I slowly add more as they get bigger and can take more ... just watch the new growth for signs of nuteburn so u can catch it ealy if you over do it ....

It's fine I use 20-10-20 for my veg and some people use 20-20-20 from veg to flower.

Perhaps starting off with 1/4 the recommended dose when I first start feeding to prevent fert burn?

Thanks All! Will my plants be okay in Pro-Mix until the first set of leaves? I have 5 in Pro-Mix and 5 in some amazing soil from my an old local gardners garden. I did ass perlite to the bottom of the buckets with the garden soil in it. Also ALL my buckets have the middle ring cut out and tons of drain holes. I plan on burying them in the ground eventually. I cut the center ring of the bucket out to allow the roots to grow into the ground if need be.