All of it depends on what the goal is in publishing the book. Is the accomplishment going to be seeing it available to buy and happy if friends and family purchase it? Or do you want that and a decent run of sales?
If its the latter, then here is what I would do. Nothing guarantee results but hopefully some of it will help you.
Who are you going to send an email to? If they are not a selected list of readers who gobble up your genre, it will end up hurting you in the long run. See this post concerning Also Boughts.
https://colony.litopia.com/threads/what-do-i-do-with-that-old-manuscript.6276/#post-74306
You are going to want 5-8 days of steady sales rather than a huge spike on day one and then a drastic fall. Think of it as a stock chart. A quick downward spike would cause investors to run away. So how do you achieve that without just luck? You need to find some book promotion sites if possible.
Assuming you launched on a Wednesday I would run targeted amazon ads for the first week and then schedule two book promotions for the following Monday and Tuesday. Your ads might serve you a few sales a day but at the end of the week with a promotion, it would sky rocket and then start triggering also boughts.
I personally dont advise pre-orders unless you have loads of fans ready to buy. To much to cover concerning them but there are more negatives than positives.
If you do decide to do promotions, avoid companies who stress they promote on FB/twitter. The results are near always horrible. Instead find those that have their own email list of readers that have signed up.
If you plan on doing no marketing, and still want to send out the emails, even to family and friends, then figure out what day is best for you. Also put a link to your signup in the front and back matter of the book and a compelling reason for the reader to give your their email. WIFM radio. Whats in it for me.
Do you promise to give them a sneak peek of new covers? Are they going to be the ones who get the first chapter of a new book before anyone else? Thats just as important as the link.
EDIT- One last thing. Your book will be in the new hot releases of your category for 30 days. The promtional money you spend during this period is the best value you will get. Thats not saying you cant advertise later without success, but its harder to get the book moving.
Hope that helps, if you want me to clarify or expand on anything just ask.