Upgrade from 4.4 to 5.4.2

Hi, I have a site currently runing Catch Kathmandu Pro v4.4 and want to upgrade it to v5.4.2 - I know I should haven't waied so long but if it ain't broke, don't fix it. It has a child theme with some customisations but ovbiously over time I have used the features of the Kathmandu theme to format the website how I want using the theme options. I know there are lots of differences in the theme dashboard between v4.4 and v5.4.2 so if I upgrade to v5.4.2 are there are special measures I should take, apart from taking a backup of everything first and will I lose any formating. I have several intermediatory versions of the theme should I go step-by-step or just do it all in one step? Thanks Paul McMahon