Thanks for the correction, my bad, はやだき is correct.

You can hear it on youtube(links include start timestamp):
https://youtu.be/PdigGRq0VV4?t=6
https://youtu.be/ppO_o--ZZ28?t=19

Straight google search: 
==== kanji ===
"早炊きモード" 109,000 (I know this is inflated, but this is clearly the common form)
==== だ ====
"早だきモード" 309
”はやだきモード"　7
”ハヤダキモード"　1
==== た ====
”早たきモード"　1
”はやたきモード"　0
”ハヤタキモード"　0

Mercari home-appliance search for はやだき: 4 rice cookers
https://jp.mercari.com/search?keyword=はやだき&category_id=7

Mercari home-appliance search for はやたき：0 hits
https://jp.mercari.com/search?keyword=はやたき&category_id=7


Android phone produces 早炊き for はやだき, nothing for はやたき (MacOS recognizes neither).  Android isn't the be-all-end-all, but it means that Japanese users have to type だき if they want the kanji.

Original reference did not provide a source for the reading(not a complaint, just a note because I don't think たき should be kept). 

I suspected this was off by analogy with:
追い炊き おいだき
湯炊き　ゆだき
粗炊き　あらだき

I now suspect that every entry in this database that ends with voiced-vowel + 炊き should probably be だき.  Several entries are missing it, some have both readings, often preferring たき(I suspect たき is often but not always spurious).   I think the shortness of these words (1 or 2 mora + daki) is getting false-positives in the n-gram corpus.

For completeness: Google N-gram Corpus Counts, but I think this is a fairly new invention.
はやたき	No matches
はやだき	24

@@ -8 +8 @@
-<reb>はやたき</reb>
+<reb>はやだき</reb>

Quiet, self-approving.

早炊き	11632
早炊き機能	689


https://www.tiger.jp/feature/ricecooker/takitate50/18.html
炊飯器の早炊き機能はどれくらい早い？
早炊きと普通炊きの違い
https://tagtag.hokkaido-gas.co.jp/portal/ecolife/appliance/2542
普通炊きと早炊きの違い。炊飯器の炊き方で味や電気代は変わる？

http://eng-ca.faq.panasonic.com/app/answers/detail/a_id/57595/~/how-to-use-the-quick-cook-function-on-a-panasonic-rice-
cooker.
How to use the Quick Cook function on a Panasonic Rice Cooker.