[DNSB]

Originally Posted by JSWolf

I prefer text-indent: 1.2em;.

Hardly relevant since the OP is likely to pick an indent they prefer.

An alternative in the CSS stylesheet to indent all but first paragraphs might be:

p { 
    text-indent: 1.5em; 
}

p:first-of-type {
    text-indent: 0;
}

Use the Extra CSS options to insert this.

Going off a vague memory, I took a quick look at the Layout options in conversion and there seems to be a setting to insert an indent when removing spacing between paragraphs. See the attached image.