u/Delicious-Spell9950

Hi all - apologies if this is an odd ask. I joined the firm about 7 months ago and was wondering how long I should wait/is appropriate (as every company is different) to refer someone? My sector has an opening (job is posted) and they have been saying they are understaffed. I have a colleague from my previous employer I think would do well/be an asset but I want to make sure I am doing what is appropriate. Thanks in advance