Puff, you crack me up.....
I dont want to speak for anyone so ill just say this...And I can only speak to this because Hemp Goddess just educated me on this exact subject...
Yield is determined by alot of factors, but the theoretical(cant spell) maximum of what you will yield is 1G/Watt. Achieving 1G/watt takes alot of experince, there are senior growers here that dont even get that much. being that it is your first grow i think striving for .05G\watt so given your particular growing situation at 400 watts 200G would be a good number to start with,,,
Okay now because you are a new grower you can further reduce that number by about half because you WILL make some mistakes, its a given... so now your at .025\watt which gives you 100 grams or just over 3 OZ. But your not done yet...
Now you have to reduce the number again because you want a Quick Grow with only 1-2 weeks veg. You also have to take into consideration that the original number was based on PEFECT Growing Environment... Temps, Humidity, Ventilation in succint harmony with the MJ....lol So Lets reduce the number again by 1/3 this time which would give you just over 1 OZ given your circumstances...
Thats the number you want to strive for and anything over that is chedder.....Youll get more yield with more experince...
And one more thing Strain has a big role in yield as well.... If I were you I would get some seeds of an autoflower or quick flower strains and go 12/12 from seed and skip the 1-2 weeks veg... Those are good for quick harvests...