When to convert from Latin1 to utf8?

Hi,

I'm upgrading a French drupal site from 4.6.3 to 4.7.4 with Mysql 4.1.20-standard, phpMyAdmin - 2.9.0.2.

I'm aware there are some issues with how the character sets are handled between versions, and it looks like I need to convert the DEFAULT CHARSET and COLLATION settings in the database to avoid problems with how accented characters are displayed. My question is, when is it best to do the conversion: before upgrading to 4.7 or after?

Thanks,

M.