water parameters

Salinity 1.025
temp 87f
ph 8.3
phosphate 1.0 mg/l
nitrate 15 mg/l
calcium 525 ppm
alkalinity 3 meg/l or 8.4 dkh
magnesium 1400 ppm

in been waiting for my tank to cycle for a good while now and i know i should wait it out and not rush any thing. im using kent reef salt mix.Phosphate levels are high and nitrate as well. calcium levels may be a little high but once things take off and i put corals in the tank it will drop. i have not been running a skimmer and don't have any fish in the tank. when is a good time for a water change and skimming. i have a small diatom bloom going on right now. when is it safe to add fish?