Does earthgrow have nutes in it? Probably will progress with deficiencies as you get closer to week 3 veg with no feeding, well atleast thats how my first 3 plants went, lol. Fed my 4th earlier due to peatmoss bare mix with nothing in it. As a first time grower, make sure your pH and ppm of intake water is appropriate, incorrect pH will cause lockout of nutrients available to the plant, if there is any in that potting mix. Mobile nutrient deficiencies will start on older growth first and progress up to newer growth, so make sure you got pH correct and know when shes hungry, as first time grower I did make quite a few of the aforementioned mistakes.
Not really experienced enough to attempt to diagnose plant deficiencies to specifics, but in general when you have problems on older growth and its progressing up, might want to think about checking what nutes are available, pH of the medium, and maybe amend with calmag if thats a bare mix, it helped me out a bit although not with the same type of dark green blotches, never experienced that myself. Good luck! I think the NPK values would be on the bag if you happen to have it, just incase you didn't know what you were working with.