send it with 120 sat and wait till confirmed it is fast and cheapest way
That's not going to work at all. At this point the recommended network fee is 960 satoshi's per byte, so your recommendation of 120 sat will make sure the transaction to stay unconfirmed for hours and hours, and maybe even for more than a day. I get it that the recommended fee is far too expensive based on its fiat value, but if you think logically, is it really worth it to wait hours and hours just to save yourself a few bucks? Sure, you could choose to use ViaBTC's accelerator, but there are so many people waiting to strike at every round hour, that it most likely won't be working for you at all, and then I haven't even mentioned those who use scripts to farm ViaBTC's accelerator....