Concurrency is not my big strength, so this will likely turn out to be a bit more clunky than necessary.

One possible trick is to use the Promise.anyof combinator to get the first of the timeout or the actual receiving action:

my $c = channel("Message");
say "Listening";
loop {
    my $timeout = Promise.in(1.75);

    my $result = start { $c.receive }
    my $combined = Promise.anyof( $result , $timeout);
    await $combined.then({ 
        if $result {
            say $result.result;
        }
        else {
            say 'timeout';
        }
    })
}
[download]

This puts a timeout on every individual .receive, but finishes early if a value is available earlier. It's also not a busy loop, so doesn't use much CPU.

I'm sure there are much more elegant solutions out there if you use a supply instead of a channel to generate the values; maybe some of the promise combinators like zip-latest can be used then.