BuddyPress.org

If you mean after logging in, put this in your theme’s functions.php

function carol_redirect_to_profile( $redirect_to_calculated, $redirect_url_specified, $user ) {

	if ( ! $user || is_wp_error( $user ) ) {
		return $redirect_to_calculated;
	}

	if ( empty( $redirect_to_calculated ) ) {
		$redirect_to_calculated = site_url();
	}

	if ( function_exists( 'bp_core_get_user_domain' ) && ! is_super_admin( $user->ID ) ) {
		$url = bp_core_get_user_domain( $user->ID );
		return $url . 'groups/';
	}

	return $redirect_to_calculated;
}

add_filter( 'login_redirect', 'carol_redirect_to_profile', 100, 3 );