no, before you srtart just backup your iphone on itunes like normal, then use quickpwn, u wil be done in 15 mins.. everything will be as it was before u pwned it except now u will have icons for cydia and installer... dont fret, it easy , check this post: https://forums.macrumors.com/threads/601085/
i finally decided to take the jailbreak plunge and read some guides here...my question is does jailbreaking erase all your data and resets the phone to factory status? will i have to redo all the settings and contacts etc?