hi mate, yep sounds like to much nutrients to me, their is a plant help guide in my signature below that shows pics of each problem and hot to solve it,
the soil your using can support the plants for anything from 3 to 5 weeks before you start feeding nutrients, all nutrients give you a schedule from day 1 but this is mainly for hydro and dwc growers as they have to use nutrients from day 1, in soil the soil contains all the nutrients the plants need until the plants are big or starting to look a light green in colour
nute burn usually shows up at the end of the leaves, so the tips of the leaves will go yellow then crispy, this is a sign the nutrients was to much for the plants, you need to remember the soil us full of microbes that are providing for the plants, so at this stage you dont need nutrients,
the leaves that are curling down do you mean the end of the leaf is curling down and starting to turn into a claw, if this is the case then again this is a sign their is to much N in the soil,
so the soil might be to hot for the plants but as the plants get bigger the soil will be ok as the plants will use up all the nutrients,
plus when you transplant this can stunt growth for anythong from 3 and upto 7 or 8 days before you notice any growth as they suffer transplant shock,
so just keep an eye on them, the plants are to small to need nutrients and if you did want to feed then id start at 1/4 strength for that age of the plant, but you could easily go 2 or more weeks with the soil their in so dont worry about nutrients for now,
just try not to over water and see how the plants get on, im sure it will all sort itself out once you get on top of the nutrients, once the plant has used up the nutrients the leaf growth will start to look a lighter shade of green, this is telling you their ready for more nutrients,
so for now id just use water, dig down into the soil about 2 or 3 inches and then pull your fingers out, if their moist and have soil stuck to them then it dont need watering, if its dry then water,
plants that are under watered will recover within an hour or 2, but over watered plants can easily take a week or 2 depending on pot size and how much water is in the pot,
a good way of knowing when their ready for water is to fill another pot with the same grow medium and leave it dry, then you have something to compare that weight to,
another option is to look at the edges of the pot, once the soil starts to dry out the soil shrinks and you get a gap running around the edge of put due to the soil shrinking,
but for now if say the plant are ok, flushing will only cause more problems like root rot, if the plants gets much worse then you will need to flush but the pics look ok to me and just looks like its had to much nutrients so just use water to feed them with for at least a week or 2 before you think about using nutrients.
we also have a new sponsor on the site that looks like he got some amazing products that you cant get wrong when feeding,
he sells 3 bags of powder nutrients that you just add to water,
the 1st bag is seedlings and cloneesm
2nd bag is veg stage
3rd bag is flower stage, you dont need to mix anything up at all, just use the bags in the right order and thats all you ned to do, the sponsor does a sample pack for pretty cheap which should be ok to run 1 or 2 plants through so you can try the products, im going to give it a try myself once im out of nutrients as it sounds very easy to use and you cant really mess it up as your not mixing anything at all, you just add the powder to water and water the plants,
here is the link
Doggett & Simpson - Growers' Gallery