Insert $DB::single = 1; in your code at the point that you want to transfer control back to the debugger. This really helps avoid having to do a bunch of manual c commands at the debugger command line, and it allows you to have a conditional breakpoint that only triggers when the desired data is encountered.
You can add commands to your ~/.perldb to customize your debugger experience.
A very common thing that people add to their ~/.perldb is:
sub afterinit {
push @DB::typeahead, "b 45", "c init_everything";
}
This allows you to stuff specific debugger commands (not Perl commands) into the buffer, to be processed as soon as the debugger finishes initializing.
(or, you can use a slightly more elaborate setup to have a separate .rc file that contains debugger commands that should run at startup)