has anyone used henna dyes during pregnancy?

I know they say it's technically ok to dye hair while pregnant since there is no proof it harms the baby. But i'd rather err on the side of caution. Im only 33 and have tons of grays, probably more than 50% gray although I never let it grow out that long to tell for sure. Im ttc again this month, and my next hair appt isn't for awhile. If i get pregnant wait till im out of my first trimester i will be really, really gray and very unhappy about that. Any one ever try the henna dyes as alternatives? I know they might not last as long but im considering a round or two of that till i can start dying again with salon dye. looking for brand suggestions or if it did/did mot work well for you