i think to start it with 3 for now and later put more 3 ... but the point is do you think i will make a good profit witht this
1. Do not buy equipment on credit
2. Start small, scale up when you see it's working.
3. More GPUs; More Problems. - (Power draw, heat dissipation) Can the electrical wiring in your house handle 20 GPU's mining at once? Probably no.
4. It's impossible to say for sure how profitable (if at all) it will be.
Up to 6 GPU is easy to handle. After that you get start to get serious issues with heat and power most likely.
But getting 6 GPU's to work on 1 motherboard is POSSIBLE but damn hard. Not sure how it is today but this was the case about 2 years ago.
Your computer will most likely only detect 4 or 5 out of 6 cards and you will be scratching your head for a month how to fix it.