The answer to this question resides in Sikh Rehat Maryada (SRM). As far as I know there is no suggestion in SRM that women who have taken Pahul must wear dastar.
SRM is the collective thought and the unified voice of the Sikh Panth on such matters. It is not written by a few the so called Takhadars of Sikhi or head priests of gurudawars; it is compiled by more than 30 very well informed, thoughtful, and diligent Sikh scholars of outstanding repute. So let us not put aside this key guiding document that all Sikhs ( men and women ) should follow.
There is no mention in this document about this issue.
However, there is no restriction if a Sikh woman chooses to wear dastar - it is her personal choice but then making a claim that it is the requirements of Sikh faith for women to wear dastar is wrong and misleading.
We don't have any record that would suggest that Guru Sahib ( 10th Guru Sahib) instructed women to wear dastar either.
So how did this trend emerge? This is from our Babas and Dera and other self interests who have put aside the SRM and have started their own Sikh Maryadas perhaps to immortalize themselves among their followers. Gurbani teaches us about equality but these trends are very divisive.
I know there are some very well placed Sikh women ( lawyers and doctors) who wear dastar. Can anyone of these women come forward and please tell us if they know more about Sikhi and Sikh Maryada than the group of prominent Sikh scholars who compiled SRM. Or they should justify their claim ( if they so claim) that is it is an edict issued by Guru sahib or any other such edict that suggests that it is a requirement of Sikh faith. Equality is paramount is Sikh faith, let us please not be divisive by presenting ourselves to be a better Sikh just by wearing dastar - there is a lot more to Sikh faith in Gurrbani (AGGS) than a focus on outward appearance especially if it is beyond what 10th Guru sahib prescribed.
If a Sikh women ( and for that matter any woman Sikh or non-Sikh) wears dastar/turban as a personal choice we must support her and her choice as long as she does not claim or preach that it is the requirement of the Sikh faith -- it is not a requirement as per SRM!
WJKK WJKF