I think you want a known baptism event to show (on limited space reports such as pedigree chart when there is no birth event available.
I think this is not possible in UFT. I think the birth, marriage, and death events are 'hard' wired to these reports. I think the user may not change that.
However, and it is a lot of work for what you det, it is possible for text to be added to birth and death events, you could enter the baptism (or burial) date in the birth event spot but add text explaining this is a baptism date. Then, I think a footnote would be attached to the pedigree chart date but you would want to print the footnotes, (a separate step) for the pedigree report.
Another possibility is to enter the baptism date as known and also the birth date as "bef 3 Nov 1822". If you are a purist, that would not necessarily be correct either since the babe could have been baptized on the same day as born.
Apply these arguments for died "before ___" whatever is the burial date.
I checked TMG and found that when there is only a baptism date, the pedigree chart uses that date BUT does not say baptism in the limited space but "b. 3 Apr 1762". And who is to know, looking only at the pedigree chart that b. means baptism not birth?