The trains run on the same schedule as on a Sunday.

So if you check the Journey planner for a random Sunday you'll be able to see the frequency and times.

Every year the timetable changes in December, normally you'll be able to plan your Journey in Oktober.

It's to early to give a right answer. About 11 december will be a new schedule.

The new 2023 schedule will start on december 11th. A few days ago NS announce that in the new 2023 schedule there will be less trains in general. On Christmas day trains will run as on a Sunday. In the new 2023 schedule it is announced that during weekends there will be 2 instead of the usual 4 IC's and sprinters per hour. 

You can read the plans at https://locov.nl/publicaties/2289378.aspx?t=Adviesaanvraag-aanpassing-Dienstregeling-2023-

De Intercity tussen Den Haag Centraal, Leiden Centraal, Haarlem en Amsterdam Centraal (serie 2100) rijdt alleen in de brede spitsturen op maandag, dinsdag en donderdag. Reizigers kunnen buiten die periode gebruik maken van de overige Intercity’s (twee keer per uur, met overstap in Leiden)

NS verlaagt de frequentie tussen Amsterdam Centraal en Haarlem van vier naar twee Sprinters per uur. De Sprinter Amsterdam Centraal – Haarlem – Alkmaar – Hoorn (serie 4800) blijft rijden, de Sprinter van en naar Zandvoort rijdt tot Haarlem. NS zoekt nog naar een optimalisatie van de aansluitingen in Haarlem van en naar Zandvoort

Still at least several trains/hr-more in the afternoon. Trip takes less as 20 mins so you should be allright.

Depending on where you stay in H and where to go in A-there are even also 2 buslines, also running ev 30 mins even that day.