Delta is the first app that allows you to add 'custom coins' for recording ICO investments. This means you can properly track your investment and just merge it with the current listing when the coin becomes tradable!
Here's how to add a 'custom coin':
In your portfolio tab, tap the 'plus' icon and add a manual transaction.
Select 'Add Custom Coin' at the top of the page.
Fill out the details about your ICO investment and then add the transaction. The coin you invested with goes in the 'Bought with' field (for example ETH) and the fiat price of ETH set by the company doing the ICO (or the then rate of ETH) goes in the 'Exchange rate' field.
Once your coin hits exchanges we support, you can merge it with a tradable coin. To learn how to do this, follow this guide here.
You can also watch a video on how to do this, but it is on an outdated version of Delta and so the process might be a little different on the newer app.