Which Elgg version?

version 3

1 - Disable 'Activity' plugin.

2 - Add in your custom plugin:

mod\custom_plugin\views\default\resources\

File

index.php

With this code:

forward(elgg_generate_url('default:object:blog'));

and for version 2.3 ?

Use your own custom plugin.

(You can use this Skeleton plugin for Elgg 2).

Add these hooks in start.php

Override this view:

\views\default\resources\index.php

Or add the redirect in there, e.g.:

forward('blog');

Place your custom plugin at the bottom on the Plugins page and activate it.