Your configuration seems OK so far, but your CPU is rather weak. When rendering on GPU, some tasks are also done by CPU, the BVH for example (BVH = building the scene volume hierarchy).
Further reading: https://wiki.blender.org/index.php/Dev:Source/Render/Cycles/BVH
I'd recommend an i5 or something similar with 4+ cores. Don't try to save money on your computers brain. Also important: don't put in 16 gB of RAM as one module, it is more efficient to put in 2 x 8 gB modules to the two fastest RAM lanes on the mainboard (usually those are color-coded). When you want to put in more GPUs in the future, consider choosing a bigger PSU. 450 watt seem OK for two 1050ti, but if you double that in the future, you might hit the maximum wattage and your cards will slow down under full stress (the clock speed will be reduced to cope with the low power = slower rendering). This will also happen, when your system isn't cooled well. With two or more graphics cards, you need to pay close attention to cooling. Make sure your case is bigger than normal cases and has a lot of fans (as many as your PSU/mainboard can supply). I can't stress this point enough, I almost melted my pc last month. I'd also recommend that you put in an additional harddrive as a framestore, 275 gB is sufficient for your OS and some few programs, but when you choose to render a lot, you will need more space for your projects and renders. This "framestore" doesn't need to be an SSD. As for the SSD, you might also consider a M.2 module. This is an SSD module, that is directly put onto your mainboard. But make sure there are enough PCIe slots available, to hold an M.2 SSD and your graphic cards.
A little disclaimer: I'm not an expert, so any comments and corrections by the community are appreciated. Those are just some empirical points from my own hardware fails :-)