You should receive a notification almost immediately. Did you confirm that this wasn't a new submission?
The FREE account gives you one active form and 50 responses at any given time. You can delete the form and create another one once you are done collecting response with the first workflow. Same for responses. You can always export you responses than delete the rows to be able to receive more responses.
If you want to collect more responses then you can look into the Basic and Plus account.
Email notifications is a paid feature but then you mention the 50 responses limit which is for the free account... So I'm not sure what type of account you currently have.
My account is a free one, with a single form.
Since it was set up last October there have been five submissions, the earliest in November, and only on 1 September have I been notified of any submission at all.
If the most basic community forums and discussions routinely notify contributions to a thread by email, why couldn't Adobe? The result is that new contacts submitting their details and payments have received poor service or none at all, thanks to Adobe's failure to deliver a routine alert.
Email notifications are part of a paid Account (Basic or Plus).
We send notifications for free accounts at 5, 45 and 50 to warn people that if they don't upgrade they could lose responses. At the top of the View Responses tab it displays the limit.