If not, then one crowd-sourcing appeal:
a. Open this google spreadsheet and request editing access (I'll approve if you don't sound like a spammer), or just do commenting:
b. Using the PDF mentioned above, find in the voting (also called "polling") date for the constituency, and paste it into this sheet. You can start from pg.63 onwards..
Some states are happening all at-a-go so those should be easier to tag.
If yes, then pls ignore a & b and just share link to the interactive map, thanks much!
How filling the google spreadsheet can help:
I have shapefile with these columns. I can merge back in the election dates and publish the map.
Disclaimer : it's directly a render of the datameet 2019 PCs data, with a 100meter simplification done to reduce size. there are gaps in the shape data and some areas left out. That doesn't mean those folks can't vote, pls don't take it that way.