Restriction Joindate [How can I do?]

[yeppuda]

Hi everyone;
I use vbulletin 3.8.10.

I want to restriction thread/forum BASED ON users joindate.


For example:
Member a joindate=May 2014
Member b joindate= Jan 2017
Thread id=100--> "showthread.php?t=100" (thread or forum)

I want to Member A can see "showthread.php?t=100"
But Member B can not see "showthread.php?t=100"

how can I do <if condition="$post[joindate]<2015"> Member A can see possible, Member B can not see</if>

how is it vbulletin 3.8 syntax?

Thanks...

PS: sory my english is little :(