How many days it take to prepare ielts?

If you're already proficient, you don't need to prepare, just show up - it's not ridiculously hard as some may think. But if you're not, you could always use some weeks, months or years depending on where you're at and where you want to be by the time you sit the exam.

Depends on your current skill in English language.30 days for >7 score if English has been your medium of instruction and you are confident in the language as such. In that case you just need to get used to the IELTS format,types of questions and timing.