Answer it immediately.
At first I thought it might be dangerous, signalling our existence to a potentially hostile species. After all, their signal could be disguised to conceal their real nature. But after thinking about it, I figure I'll probably be dead long before our reply is received. so it will make no difference to me.
Does that sound selfish? Maybe so, but its how we're responding to global warming and the Covid epidemic--milk it for all its worth now and let the future handle the consequences...