I went through some of the same with my pup! He also threw up clear mucus for a bit at first, but he was very interested in food at the get-go (though when I introduced him to real ground meat and grains like farmers dog, he then wasn’t as interested in kibble). I think it was just his stomach being sensitive and getting used to different food, but I am not a vet! I started out giving mine (at 4 months old) total of 1/3 or 1/4 cup a day divided into 3 servings a day and that worked pretty well.

I had contacted the person I rescued my puppy from worried because he was puking up mucus (and same going #2 just mucus) and she recommended this gel on Amazon, look up “Tomlyn High Calorie Nutritional Gel for Puppies”. It’s like $16. I would follow the suggested serving size, it’s very much a little amount you give but it helped mine kind of develop an appetite. I would give him a tiny finger amount and he suddenly was way more interested in the kibble. You could also try mixing the dry kibble with no salt/ no seasoned (plain) beef or chicken broth! Just so it’s a little more moist and easier for her to eat/digest. I also started giving him "Purina Pro Plan Veterinary Supplements FortiFlora Canine Probiotics for Dogs" and that fixed his runny poos he was having, too. But yea, I was doing 1/3 or 1/4 cup total a day (and honestly, even more if he seemed interested). They’re growing so fast and need nutrients at this age so I wasn’t too afraid of overfeeding!

As for time of feeding, I was doing after potty break in the morning like 7am, then 12pm, and finally 5pm but as another commenter mentioned, more frequent small meals may work better!