if you have if you have free electricity and 10k cash
how much you will invest in bitcoin mining and when ?? right now or later and why
The reality of mining is that the larger players are making the money - you as a small player are going to have to pay a premium for your mining equipment so even with free electricity, you are in all likelihood not going to break even. Do you have power supplies for the miners? If not you have to buy those too.
Antminer S7 (batch 13) - $637
Recommended PSU - $140
---------------------- --------
Total $777
You also have to pay shipping and I would imagine your government will want some taxes and/or duty... maybe even a bribe to let it come into the country.
Now, running flat out @ 4.76 TH/s you can presently make about $6 per day in bitcoin. Reduce that by 5% in the next day and a bit when the difficulty changes so we might as well start at $5.70 per day. Let's say you get lucky and the duty/shipping and taxes are only $123 so your initial outlay is $900 for an Antminer S7 (it will be more).
900/5.7 (let's not even think about the difficulty change every 14 days yet)
You're looking at 158 days to get your money back but wait, there's a reward halving in 117 days! After 117 days, you'll have made $667 and you'll need another 81 days after the halving to make up the remaining $233. All in all, not considering the difficulty changes if you can start tomorrow, you're looking at 198 days conservatively to get your initial outlay back and that's IF there are no difficulty changes and IF the device runs that long without problems. Also, most pools are going to charge you a fee to let you mine (usually 2%); don't forget to subtract that.
Maybe you can get some cheap S5s - they run at a paltry 1.155 TH/s so you're going to see about $1.45 per day from it. You might save some money per TH in buying that over an S7 but it's already been well used and likely to have issues. Also, you still need a power supply and the shipping isn't going to be any cheaper for buying an obsolete device.
You can play with the number here:
Bitcoin Mining Profit CalculatorI believe the "Growth" is for each 14 day period. The next "Growth", will be 5% but you can enter a longer term estimate.
Also, since your electricity is "free" just enter 0 for "Power usage" or "Cost per kWh" (or both wouldn't hurt)
TL;DR - Unless you need a noisy, heat-producing hobby, forget about mining. If it's bitcoin you want, buy bitcoin rather than mine.