Should I tell people I'm trans at a prospective volunteer place?

[The Flying Lemur]

This is new territory for me as I don't work because I'm on disability.  I'm looking at volunteering at a local charity, and I'm not sure whether I want to send them an e-mail saying, "Look, I'm trans, I don't pass especially well, but I'd like you to use my preferred name and pronouns."  I live in a pretty progressive city, so I don't think they'd "fire" me on the basis of gender identity alone.  My other option is to wait until I'm actually in training, and just tell everyone in the room my preferred name, and then politely correct them as they all proceed to misgender me. 

To be honest, both options sound fairly mortifying, but I'll be damned if I'll go by my birth name and female pronouns all the time. 

[AnamethatstartswithE]

Unless it's they type of charity that involves background checks you can just introduce yourself as [preferred name]. I don't see why they need to know.

[Devlyn]

That's what I was thinking.

Volunteering at the front desk at the hospital? Whatever your ID says.

Cleaning the local river? "I'm Jim"

Hugs, Devlyn

[The Flying Lemur]

Oh, I agree with you that it shouldn't matter, but the reality is if I just show up and say "Hi, my name is Ben," they're going to think, "Well, that's a weird name for a woman," and then proceed to call me "she" and "her."  I'll need to either correct each of them every time, or else just rip the band-aid off and tell them all before they meet me.

[Devlyn]

Ask the group management. They may already have experience with this.

Hugs, Devlyn

[Jin]

I never tell anyone, unless they specifically ask. Then I simply state the truth.
On forms I often write "NUNYA", as in None of your Business.

[elkie-t]

To be honest, both options sound fairly mortifying, but I'll be damned if I'll go by my birth name and female pronouns all the time.

Do you have your documents changed? If so, no need to tell anyone. People have eyes, they may see what they can, but legally they go by your official name  and gender. And no need to either confirm or deny anything related to your past...

Now, if your transition is not legally completed and you are asking for a favor - to address you as you desire and not by your official name - then you need to ask for a favor.

Speaking of other volunteers / stuff members / etc - I'd suggest to dress unquestionably masculine/feminine, wear your name tag visibly and if they are making a mistake of not understanding your correct pronouns, to correct them once. If it is repeated, I'd bring it to the management. But that can be done only after the management itself is on board with you

Edit: sorry, thought the OP is a MTF. My mistake, cannot edit my properly as I am driving now