Here is my advice for you:
1 - Mix the links, don't build a 500 backlinks for the main page, make some backlinks for inner pages too, and use a related keyword for each page.
2 - If you are going to make too much backlinks in one day, then don't ping all those links once, since you are telling Google that you did it and its not natural.
3 - Quality not quantity, it's better to pick up the forums that are related to your niche, the backlink will be much better.