Should I get 16gb of ram straigh away or should I get 8gb of ram then upgrade?

[thepcgamer099]

should i just buy the 16gb ram straight up and then it will work together well or buy another 8gb later on (which i have been told isn't a great idea as it may not work well, even though it is the same type) or won't i ever need 16gb ram by the way i am not too fussed about the price but i need to know whether i will ever need 16gb ram to keep my high end gaming pc playing games on high settings fast whilst recording. Also my monitor resolutions would be 1920X1080. also I will be slightly over clocking but not massively and is my system compatible.
Here is my system;
Intel i5 4670k
Gigabyte z87x-d3h
msi 4gb gtx 770 twin forzr 2 (the price difference isn't much between 4gb and 2gb so i wouldn't be able to downgrade 2gb and get better parts or anything)
crucial ballistix tactical RAM 16gb (or 8gb and then upgrade, which apparently isn't a good decision)
Seagate 3 TB HDD Hard drive
Samsung 120GB SSD hard drive
Aerocool X-Predator X3 Evil Gaming Case
Corsair CX 750w
Cooler Master Hyper 212 EVO
Creative Audigy SE 7.1/PCI Bulk Sound Card internal PCI
Creative Inspire T6300 5.1 Surround Speaker System with Remote

Thanks in advance

 

[Tradesman1]

Best if you can just get the 16GB now, mixing sets of DRAM even of the same exact model can be problematic, plus if you do it now, can go 2x8GB which would be less stress than trying not only mixing sticks but then running 4x4GB