you can do this in two ways; 

The first way; create a campaign with the commits phase enabled, this way you can collect the interest of users without charging them because Commits is a phase where only emails are collected. When you hit your commits goal; you will be able to start pre-orders manually and all the committers will receive an email notification that the pre-orders phase has started. 
If you don't want to start taking pre-orders automatically when you hit your commits goal, you need to disable the "Start the pre-orders phase when the target number of commits is reached" checkbox; what this does is give you control over when you start taking pre-orders and when you're happy with how many commits you got, you can start taking pre-orders, and during the pre-order phase, payments are collected. and you have 7 days to capture those payments or as per your Shopify payment settings.


The second way; If you want to skip the commits phase, and you want to start taking pre-orders immediately, but not collect payments from your customers just yet - See this video on how to skip commits; https://youtu.be/pTQjfjkFsyk

By skipping commits, you'll be able to uncheck the "Enable direct checkout during the pre-order phase" by doing so, your backers will be able to pre-order only by submitting their email, your backers pre-orders will be recorded as Draft Orders and will appear all at once when your campaign ends or when you choose to end it manually.

Draft orders are powerful, you can invoice your backers who pre-ordered individually, and you can also collect cash on delivery, it gives you full control over how you'd like to fulfill your draft orders, customize them or add a discount to them before sending them to your clients.


As you can see, each way has its own advantages, it all depends on the goal you're trying to achieve with your campaign, whether you want to collect payments from your backers or you want to charge them only when you hit your pre-order goal.