Advanced Subscription Start Date - How to set up?

I am trying to set up a plan with Advanced Subscription Start Date.
With this plan Users will be able to set up their own start date for the plan. We want this date to be a date in the future. i.e. minimum is tomorrow 
On the Plan in Advanced Settings, I set Subscription Start Date option to be 'Determined by Customer'
I set up  a Custom Date field for this plan and associate that custom field with the Subscription Start Date Field in Advanced settings
In the Custom Field I set type to Date
In the Data Validation settings, I want to check that the date the user enters is a date in the future. This is where I have the problem
I read the MP documentation on this  membershipprodoc.joomservices.com/basic-...scription-start-date  
and the section
membershipprodoc.joomservices.com/basic-...eld-data-client-side
in the above is information on how to set up date type validation. the text is as follows
"Date type vailidation: When you select an option, the system will insert the related rules into Validation Rules automatically. For example, when you select Min integer, the system will insert validate[required,custom[integer],min[-5]], of curse, you will need to change -5 to the correct value you want."
The setting of min integer for a date field does not sound logical to me?? does -5 mean the date is must be a least 5 days ago?
There is also another section
See  posabsolute.github.io/jQuery-Validation-Engine/#validators  for list of validators supported by this library and use the one meets your need.
But when I click on this link it does not take me anywhere as if the link is broken, so I can see anymore information on these field validations
My Question is:
1)How can I set date validation to ensure the user can only input a date in the future? i.e. Tomorrow, next day, day after next day etc.
Also, a supplementary question
 For a Cutom field type Date is it possible to set a Default Value of 'tomorrow' in the default value?
Kind regards
David
Note: I did find this on Validation
www.jqueryscript.net/form/Powerful-jQuer...lidation-Engine.html
 

Hello

You can use this rule github.com/posabsolute/jQuery-Validation...nother-elements-name

So set the validation rule to validate[required,custom[date],future[now]] . It compare to current date, not tomorrow, but it should still be useful

Regards,

Tuan

Thanks Tuan,That works fine.
Just one minor issue.
I set up the Validation Error Message. However, the message is not displayed, it displays what appears to be the default message, which is not clear to a user. Is there something else I should do to display my message instead pof the default message?

For other users. Please see attached screen shot of custom field settings as propsed by Tuan