Upgrade vBulletin from 3.7.2 to vBulletin 5 Connect

Upgrade vBulletin from 3.7.2 patch 1 to latest vBulletin 5 Connect. I have upgrade license. It is recommended to upgrade to 3.8.7 version first, and from there it can directly upgrade to VB5. There are 3 plugins which may or may not be need to upgrade depending on new functionality in version 5. The current plugins are: FractalizeR: Registration Form AJAX Enhancements -- 1.1.7 Enchances registration form with AJAX Members who have Visited-- 3.7.004 Display members who have visited the forum. NoSpam! -- 4.0 NoSpam! allows you to specify a set of questions which members are required to answer correctly at registration, eliminating the ability of spam bots to register at your forums and post unwanted messages. The forum is also integrated with main site which may need or may not need some modification also. Would like suggestions on best way to do this as not to interrupt live site until upgrade is completed.