I use oral cleanser and oral wipes to clean their gums and tongue from newborn onwards!
Products that I bought and used:
(Disclaimer: not Shopee affiliate)
Oral wipes:
https://sg.shp.ee/prBmJ2R
https://sg.shp.ee/nwKQYML
Oral cleaner:
https://sg.shp.ee/DCeEWyR