I get 8 ozs with a 400 and think it would be unrealistic to say you could do it with a 250w.
If its your first time, I would say your likely to get 4-5 ozs.
Having a yield goal is a disappointment waiting to happen. The main goal is to have a harvest free of disease and pests that has been allowed to finish.
Listen to the caveman projected numbers are a disaster waiting to happen especially with all the other problems that can ruin a crop . Sure you will do well with all the help around here tho .
your goal should be enough weed to get ya to next harvest without having to buy any ! just dont grow all the same strain, mix it up , will help ya stretch it longer
Just keep them healthy and you will be so proud at harvest. Keep moving them a quarter turn a day to get all around exposure to the light. This is also a good time to feel for light plants that need water ( never water the heavey pots). Always remove dead leaves asap. Put up a sticky trap to identify any bugs that may show up, seen in traps (like tape flags) before over run with an infestation. Watch your temperature and humidity, keep posting. Any amount at harvest is good.
Yeah, everyone is right bro...the most important thing, before any weights, is a happy plant and growing enviroment..once those are down, you'll be seeing huge returns on all that work...
take care and happy growing!!