We haven't ventured out of the neighborhood much in our first month... a couple of appointments and a few errands. When we have, this is what I've brought along with us and it will likely be the same for the next month or so.
I like to change up my bags every season and figured I would want to do the same with Alexa's diaper bag. I decided to register for the Skip Hop Jump Pronto! Changing Station and Wet/Dry Bag to turn an LL Bean Boat and Tote (medium size with regular handles) into a diaper bag for the spring and summer. There are other inserts out there but they can be pricey. This is an affordable way to turn any tote into a diaper bag.
Change of clothes/Ziploc bags in case of a blow out
Honest Hand Sanitizer
Honest Organic Healing Balm (This is the travel size from the free trial)
Honest Wipes (The organize also comes with a plastic wipes case)
I also pack a burp cloth, ring toy, and swaddle blanket to use as a nursing cover. Since I am breastfeeding it eliminates the need for items you may otherwise need in your bag. I did get the coordinating Skip Hop Jump Bottle Bag to use when nursing comes to an end.
At the end of the day (or whenever I have the chance) I will restock the bag as needed and place it in her carrier. That way I'm ready to go for the next outing.
As time goes on there will be more to add (sunscreen, teethers, toys, books) and I'll probably have to upgrade to the large size tote. Did I leave out any of your diaper bag essentials?