The amount of time it takes to build a campaign page may vary depending on a lot of factors. Keep in mind that all sections of your campaign write-up editor need to be filled before you will be able to send it for review.
There is no deadline to complete and submit your campaign; you can always revisit it again at a later time and only submit when you are ready.
It’s completely up to the campaigners to choose their campaign duration, with the minimum duration of a month. So make sure you give yourself ample time to prepare. Once you think you are ready, submit your campaign form. After validation and the date of the start of the campaign is reached, your campaign will start.