I think the bounty help page has good advice:
"If you’ve asked a good question, edited it with status and progress updates, and still are not receiving answers, you can draw attention to your question by placing a bounty on it."
- Ask the question
- Give it a few days to see if it attracts a good answer or not
- If not, try to edit the question into shape
- Give it a few more days or so
- Assess if the question still isn't receiving good answers
- Decide if you still need an answer
- Then place a bounty and hope for better answers
Maybe it will work, maybe it won't. I haven't seen convincing evidence that a bounty will often attract great answers to a question that hasn't already attracted them. As far as I can tell, if you are going to get a really good answer, you'll get it very quickly after asking the question or not at all.
But I could be wrong.