Is this a good time to start trying to give her romantic gestures like flowers or cooking for her, etc. or should I wait on stuff like that? (I have a feeling that flowers may still be rejected.)
No, do not do any of that b/c you will need to continue to hold back from any romantic gestures of any kind until she is completely over the OM. You saw how she rejected holding hands with you (which I think is a romantic gesture) and she will reject any other pursuing action. I promise you it will backfire if you try it.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!