Well, It is not a big issues these days. Google is smart enough. I totally agree with martin in this. Secondly, your title of the post would automatically be in H1 which would fulfill the requirements of having H1 tag in the post.
However, the thing which matters a lot is the on-page SEO of your site. On-page SEO of your website should be perfect.
Like your main keyword should be in H2, and all other headings which you consider important must be in H3 or H4 whatever you want as per your website's design. Moreover, do not forget to add Schema ( Google Structure Data to your site ).
I have done on-page SEO of my website properly, and have achieved good rankings after the google core may update.
