Need some HELP!!!

Hey everyone,
I'm doing a grow and needed some help on a few things. It has been 10 days since my seedling broke the surface. It was going great until I noticed the end tips of my leaves were getting a bit yellowish/brownish color. I want to save this plant and I know if I caught it early enough it would be possible. Any help and info would be awesome!
Here is a list of everything I've been using in my grow medium:
SOIL- Fafard Organic Potting Mix
LIGHT CYCLE - First 8 days was 24/7 lights on. I just started doing an 20/4 cycle and started hardening off outside for an hour each day (I'm going to increase by 30 mins each day until I'm ready to plant directly outdoors). I should be ready to plant outside in another week (unless you tell me it's ok to transplant sooner).
WATERING- I have been using well water for the watering. My town has really good water, so I don't think that's the problem. I've been watering whenever the soil is dry an inch or two down from the surface. So I doubt the yellowing is due to overwatering.
FERTILIZER- I have a 10-10-10 fert made by Scotts, I have another 19-6-12 made by Expert Gardener (which of these ferts should I start with?) I also have a 10-15-10 for flowering. I applied my first application of ferts 2 days ago. A very very very weak application. I used my fingers and applied one pinch to the plant of the 10-10-10 fert.
Egg Shells- I started giving my plant crushed up egg shells for a Calcium boost. I only gave it one application of this so far. The first application of egg shells was given to the plant 4 days ago.
Any help would be greatly appreciated guys! I uploaded a few pics so you could see what I'm talking about.
So my questions are; What is the cause for the end tips of my leaves turning yellow? When should I go ahead and transplant directly outside? Which fert should I start with?
Thanks!

First off, you jumped the gun on fertilizing. There is no reason those little seedlings need you to shove a buffet in their face and expect them to eat it all. I would either flush thoroughly, or transplant quickly into fresh soil, and I recommend the later. Your base soil should be enough nutrition to get them through a month.

I agree no need to feed yet, that's probably why they are browning at the edges....I don't think you need to flush unless it gets worse but I would give only fresh water for awhile....

youre using really commercial ferts not meant for cannabis necessarily...you can use it don't get me wrong (there are very few MJ ferts anyway and they're expensive) but you need very little and wait at least a month before starting to feed...

youll be fine tho they should bounce back...I like to over feed about 6-7 weeks into flower, just enough to brown the leaf tips...it's pretty hard to kill these plants lol

I wouldn't flush again. Since you're using dry ferts, it wont really matter, it takes more than a couple flushings to really break down the nutrients and make them avail to your plants.

If you water everyday you'll end up killing that thing. Let your soil dry to encourage root growth.

Get some Pro-mix soil or a Peat/perlite/soil mix. I only use nutes after the 2nd week and even then its a fairly weak dose like 5-5-5.