What motherboard are you currently using? Pretty much anything you could be using with your 7600 is not going to support a 9700k. So you will need a new motherboard regardless. Only the 3XX mobo's support 9th gen or 8th gen chips, such as Z370 or Z390. Your board (H270 or Z270?) may have the same socket as say a Z390 or Z370 board but it will not support a 9700k.
You will certainly see a performance uplift going from a 1060 to 2060 with your i5 7600 in most games, just not as much as there would be if you had a more powerful cpu. So yeah I would upgrade the GPU first if you cant do both at the same time.