Welcome to RIU! Always nice to see new growers join! I myself am a first time grower and have found great advice from this site. Take in the information people give you, but also be willing to do your own research as well. The search tool on RIU can really help prevent you from asking questions that have been asked a thousand times. The reality is it is your grow, and YOU have to make the final decisions with your grow!
As far as any advice, I recommend being careful with the nutes especially with mg soil. MG soil often has time release nutes in the soil already, and mixed with fox farm you could possible run into some issues of your plants being over fed. I haven't used mg soil as I have read many bad things, however I have also seen some great grows done it. Just keep an eye on the plants for any signs of nutrient burn, etc.
Best of luck with your first grow! Definitely no expert here, but if you ever have a question don't hesitate to ask. I will do my best to try and help or if nothing else someone here should have an answer for you!