Clint,
I don’t know about Belgium, but in the UK, the norm is a month for most
people and 3 months for senior members of staff. Of course, you may or
may not be given work to do during that period. Usually your employers
will want you to document and help hand over to a new person. However if
you have a bad relationship with your employers, they may put you on garden
leave where you arent in the office, but are being paid. Presumably
this is to stop you stealing their data or doing some other malicious
act. All this stuff is normally written into your employment contract.
Without one it is possible to leave your employer within
a week.