Too late to find stolen iPhone?

Hi, I had my iPhone stolen 2 days ago. It was a 4s, but I just bought it in May 2013 from a verizon store. I didn't have one of those tracking apps downloaded, but I heard it doesn't matter bc iCloud should be able to track the phone. Is it too late bc I don't have iCloud downloaded? I tried calling it several times but it just goes straight to voicemail. I'm hoping there's some way I can still get it back bc I had so many pictures and memories on it, does the fact it's a newer one help at all? Please if anyone can help, thank you

Do you still have your iPhone box?

If you do, you can find your serial number and IMEI/MEID printed on the barcode label that's affixed to the packaging.

With the IMEI code, the police can track it so file a report if you're really desperate.

If you have another apple product then download the app and whenever you find it make sure that the first thing you do is download the app on it just in case