My first cycle was test e 250-300mg per week for 12 wks. By week 10 I was up 30lbs. This was after 25 yrs lifting natural. I was at around 5'10 190 10% when I started wich is about maxed out for natural. I ate more cals than I needed , but I wanted to make the most of it. Of course I put on some fat , but I put on a lot of muscle too. It is mostly diet imo. You can gain 5 lbs or 40lbs. it depends. But my advice is too keep the diet clean & add like 500-1000 cals to yeur current diet. Don't only look at the scale just trying to gain the most weight you can, but look in the mirror too & try not to gain too much fat. IMO what you do after your cycle is as important , or more important than what you do during the cycle. You need to keep eating a lot (esp. protein) or you will loose your gains, but at the same time you have to try not to get fat. That is why lots of people use aids like clen during pct. , but you can just have a strict diet and be ok. I am assuming this is you first cycle, 500mg is more than enough, I would use more like 250mg-350mg. You can always go up next time if you need to. I see people who do 500mg the first time & next 750 mg & 400 deca for a second cycle, this is a mistake IMO. But whatever you decide to do it will come down to diet.