Upgrade Monitor or Gpu first ?

[Skillrex]

1. Budget - 10- 18k
2. Display type and size - IPS is a must and with Freesync is big bonus for me !
3. What will the TV/monitor be used for primarily - Photoshop/Lightroom/Content Creating/Web developing and little bit of Gaming off course
4. Types and number of ports required - I am planing to set 2 monitor later this year.. so yea multi port is a must.
5. Preferred choice of brand - may be LG.. as after sale service is pretty good in my city.. but i am open to other brands.
6. Any TV/monitor in consideration - Nope
7. Any other info that you want to share. - My GPU is old MSI 460gtx (N460GTX Cyclone 1GD5/OC | Graphics card - The world leader in display performance | MSI Global)

I want to upgrade my monitor and gpu but i dont know which one to buy first.. as i am little cash scrapped.. I can buy only one of them first.. If i go for monitor first will it be supported by my old gpu ? or should i go for gpu now ?

My current rig -
Ryzen 2600x
MSI b450 Pro Carbon Gaming AC
Corsair Veng 16gb 3000mhz
Coolermaster 212 BE
MSI 460Gtx
Samsung 250Gb SSD
4 TB WD HDD

 

[x666x]

I've been looking for something similar. Do let me know what you went for eventually.
The most obvious choice to me is the BenQ 2420PT which is a 1440p monitor but it seems unlikely that you'll be able to run PS or Lightroom smoothly on that resolution.