How long before I can get a new verification code?

My wife's iPhone 6 was acting strangely yesterday. After entering the pass code (or using the fingerprint id), the spinning wheel would appear and then ask for the pass code again. I tried the pressing the power button and the home button but, alas, the problem continued.

I was able to backup to iTunes and reset the phone and all went well until signing into the iCloud account. 2 Step verification is turned on so after entering the password, I elected for a verification code to be sent by SMS. I didn't receive a code so tried again. Still no code was sent. I then asked for a phone call which, mercifully, happened straight away.

I entered the 6 digit code that came via the phone call but was told that this was incorrect. Then, almost immediately, 2 SMS's arrived with different verification codes. I tried both of these but, again, was told that they were incorrect. I can only assume that I somehow entered them out of sequence so I was never entering the most recently generated verification code.

A message now appears saying that too many codes have been sent and to try again later.

My question is how long do I have to wait before I can try again? The phone is useable but, of course, my wife doesn't have access to any of the apps associated with the account. They are all on screen but 'greyed out' as it were. I don't want to keep trying to log in as the account will probably be locked.