Visiting Unis: Now or will I have time to see them all on Offer Holder Days?

Hi!
I missed all the Open Days for my choices. I'm applying to 3 unis. I booked some time off work this month in which I intended to go and Visit the Unis & their cities, and do a self-guided tour of the campuses.

I just found out about Offer Holder Days. I'm wondering if I should wait out until then to visit the Cities (rather than shelling out several hundred pounds to visit now, then again next year).

On the UCAS website it says that 'If you receive your last decision on or before 16 May 2024, your reply date is 6 June 2024. If you receive your last decision on or before 17 July 2024, your reply date is 24 July 2024.'

...meaning that if my offers take a while to come , I seemingly will only have a few weeks or a few days to go and visit them.

It's important to me that I visit the Uni's before firming any offers.
Will I have time to visit them all on Offer Holder Days?
Are Offer Holders Days held frequently enough that I'm likely to be able to visit them then?

Is it worth paying the extra money to visit them now, just in case I can't visit them later in the year?

Or should I just hang on until around April, and if I don't have any offers then make the decision to go?

Is there any other info I should know, as I only just found out about Offer Holder Days... I'm wondering if there's more that I've missed.