MoBo : Gigabyte H81M-H

I really am getting impatient with money. I can buy a GTX 1050 Ti right now and replace that fucking shitty radeon, but I also want to consider buying a new PC. If I buy the GPU then my option will be to upgrade my MoBo and Processor. I'll end up reusing my Case, PSU, and hard drive and whatnot.

Will I run into any problems upgrading my gpu to the 1050 as of now?

Will it be better if I save fully and just buy a pre built pc or buy components and build one?

I just really wanna play games with my frands y'know.