If you are going ahead now with the initial documentation for an IVA and no court action has already been commenced by a creditor, bailiffs won't suddenly appear at your door.
In the first instance once you stop paying your creditors, their own collections departments will be in contact with you, once most of these are aware that an IVA is being prepared, the account will be passed to their Insolvency department. Where this does not happen, once the account has defaulted which would be after 3 months, the account would then be passed to a Debt Collection Agency or perhaps sold on to a different company. If after this time County Court proceedings are commenced by a creditor, from now to when there would be a possibility of a County Court bailiff visiting you would be between 4-5 months, during which time you would hopefully have an IVA in place.
I would add that when we are dealing with any proposals for clients, we do not advise them to stop paying their creditors and advise them that should a creditor ask for a token payment during this period that they do try to make a payment no matter how small, as nothing is guaranteed and should the proposal fail or an IVA not be possible and the creditors have not received any type of payment whatsoever, they may be on the brink of commencing legal action for which you would have no protection.