it'd also depend on whether I'm using Daiz's figures or not. but still using the more comfortable 5,000,000 spot for goku.
Goku -- 5,000,000
-- SSJ -- 250,000,000
Mecha Freeza -- 260,000,000
SSJ Trunks -- 325,000,000
SSJ Goku -- 360,000,000
-- post 3 years
Piccolo -- 410,000,000
SSJ Trunks -- 492,000,000
SSJ Goku -- 545,000,000
SSJ Vegeta -- 560,000,000
Imperfect Cell -- 616,000,000
#18 -- 740,000,000
#17 -- 820,000,000
Imperfect Cell (post) -- 1,320,000,000
#16 -- 1,300,000,000
So yeah #16 would be the 1st character to cross this mark.