Wait until you hear from somebody who has more experience, but I have researched ppm, and these are the numbers I have determined:
seedlings and clones: 100-250 ppm
10 days - 2/3 weeks: 500-600 ppm
one month - flower: 800-1000 ppm
flower: 1000 ppm, slowly raise to 1300
never exceed 1300 until experienced and always remember to check ppm of water and add to base numbers.
Again, though, I am just learning myself, and these numbers come from research not personal experience, so wait until you hear from someone who can provide some experience. General rule of thumb, though. Always best to underdo it than to overdo it.