Agreed you can charm starting as soon as you get your first charm spell. Expect to die a few times while you get the hang of it and learn your limits. Life is much easier if you are doing this outdoors at first and are able to get a SoW since when charm breaks you can create some distance and also are able to not be standign right next to where your pet is fighting.
Below is a guide that can help learn some tricks of the trade. My short version is root the thing your pet is fighting and keep your level 4 mez spell ready to mez your pet when it breaks. Be prepared to use rune line of spells to keep from taking dmg on breaks.
http://wiki.project1999.com/Loraen%27s_Enchanter_Guide
Charming is tons of fun and extremely powerful, but you will find that it requires your full attention. Alt+tab is a sure way to die while charming.