You do not need to pay the points to upgrade it to a Nob first. I don't have the Ork codex handy but if it works like any of the other special "upgrade" characters than no you do not need to pay the points. If, however, it says "Upgrade one
Nob to Snikrot" then yes you do need to pay the upgrade points first.
Note: I know your kind of new to this site but try to avoid posting points values here
GW doesn't like it when people do that and the site could get in trouble. Just letting you know for future reference.