Sometimes that isn’t commercially possible, though. If you absolutely need to tell people about the invention and an application still isn’t filed, then make sure that those who receive the information are all under a strict duty of confidentiality. Then, monitor them for compliance with that duty. If they breach it, tell your patent attorney immediately even if you don’t plan to sue them for breach of confidence.
Anything else places your patent rights at risk. Yes, there is grace period for US applications, but the patent rights in all other countries could be dead and if the disclosure starts being repeated and developed by others then you may be facing an interesting (read: expensive) time in the US Patent Office.