2nd grow - Outdoors - Purple Punch Auto

Week 1 It has been seven days since putting the seeds on a paper towel. In the meantime they have managed to crack their shells after which I transferred them into soil. It seems they like it and they managed come out of soil and started stretching. They are now reaching 3cm (No.1) and 4cm (No.2). they also have four nice round leaves. I am watering them every second day not waiting for the soil to dry too much. They are in a small compartment, designed for seedling stage, with two FL baton lights each using 25W, and a heater that keeps the temperature at 25C. I don't have the timer installed yet so I can't put them to sleep at night but since it worked the first time I will not change that yet. I am using rain water and adding just a tiny bit of Miracle Gro Soluble Plant food with N-P-K values 24-8-16. I don't want to burn them 😋 Update: day 5 of week 1 The two girls are developing nicely, adding leaves and stretching a bit. They are now 5cm and 7cm high (No.1 and No.2 respectively). I hope they keep this pace and when they move outside they should be great. I am wondering of one of you, experienced growers, can give me a hint of when to move them out. Daytime temps can climb up to 16 or even 18C but nighttime ones can drop down to a few degrees above 0C. Would either (or both) cause problem if I move them too quickly. They are not at comfy 22C.