Heroku expert needed asap for huge increase in app usage

Hi all (read on if you're around over the next 3 days to help with our app which has had a spike in usage and can't crash because people's lives depend on it..!) thank you!! Info below: We have a SAAS product which enables carers to make automated calls to the people they support. These automated calls remind the person to do things like "please remember to take your medication" or "if you need any assistance, please press 1". We've recently had a huge increase in usage (at the moment we make ~100 calls / day) and we're expected to be making 15,000 calls a day (starting on Monday...!!!!). I'm a little worried as we've tested our system for the small number of calls however this is a huge increase that I'm not that confident that it will be able to handle the new usage - please could you help? Our setup is: [login to view URL] which acts as a no-code front end as well as the database for the information on both the carers and the people being called. A Heroku server running a node.js script which, in summary, pulls the data from the bubble database and sends it to a 3rd party company which makes the outbound calls. The process for how this happens is: 1. Each day [login to view URL] sends 1 API request to the heroku server saying "it's time to get data from [login to view URL]" (the scheduling is managed by bubble) 2. Heroku receives this API request and then makes a GET request to the bubble database using the following endpoint / way of retrieving data ([login to view URL]) 3. The Heroku server then takes the the data which is has been retrieved and restructures it into a csv format which it then sends via POST request to the 3rd party company which we use to make the outbound calls. As mentioned, at the moment we're only managing restricting 150 items of data but we're expecting it to be 15,000 items of data starting on MONDAY (ahhh!) - I don't know the JSON body size right now. I'm looking for someone to - (important) get started today/tomorrow and work on the weekend to ensure this system which people's lives depend on doesn't crash - look at our server code and see if there are any areas of worry about and write & test improvements - look at our heroku set-up and see if there are areas to worry about and provide pointers on how to improve how to configure the set-up - help me sleep at night by alleviating these concerns!! Thank you! M