Buffer is good if your manually inputting however I stopped using this and moved to Postcron and used excel sheets in conjunction with this to preload around 100 links and 2000 images across 3 platforms over a 14 day period.
Customer service on buffer isn't the best like mentioned, however Postcron (if you ever use it down the line), their customer service is amazing.
Just use Bulk Buffer + Buffer. No need to add them manually, then.