since you need control over 3 components, you’ll need 3 animators.
add the first animator for opacity, this will be for the first letter. set the animator’s opacity to zero and then add an expression selector and paste this expression into the expression selector’s amount expression:
if ( textIndex == 1 ) { a = 0 } else { a = 100 }
[ a, a, a ]
to get the first letter of the second word, you can duplicate that animator, set the opacity to 100 (since the first animator set it to 0, this one will set it back to 100) and then use this expression in the expression selector:
txt = text.sourceText ;
wrd = txt.split(' ') ;
if ( textIndex == wrd[0].length + 2 ) { a = 100 } else { a = 0 }
[ a, a, a ]
now both first letters should be visible. To animate those, simply animate the opacity property of the those animators.
to get the rest of the letters to reveal, create another animator for opacity, set the opacity to 100, animate the offset property to reveal letters and set the Mode to Subtract.