Guarantor agreement - date query

Guarantor

Somewhat against my better judgement I'm offering a tenancy to a couple who are going to need a guarantor, which is something I really try to avoid due to the extra red tape and reports I've read of such agreements being notoriously hard to enforce through the courts.

I'm using the RLA Deed of Guarantee form, which I have sent to the guarantor along with the tenancy agreement. My issue is that due to ongoing delays with the guarantor's application, it now looks like we won't be able to make the envisaged start date of the tenancy this weekend, which I've entered on both the tenancy agreement I've sent her and the Deed.

Do I need to send her a whole new set of documentation with the final correct start date on it? I don't want to risk any future claim being thrown out, eg because the guarantor's seen a 'different' (albeit identically worded) tenancy agreement. Also, the plan is that the tenancy is ready to start the second I have the signed Deed in my hands, so nobody wants the start date simply to be some arbitrary 'safe' date in the future.