IPhone 4s 1GB DATA? How much app time can i actually have?

I just purchased an iPhone 4s, I have 250 mins and unlimited texts with 1GB of data.

I only really use apps such as instagram, facebok, twitter etc.
How much time can i actually use on these?

I don't want to go over and pay more, I'm already paying £31 a month

Added (1). So if i'm connected to Wi-Fi i won't use any data?

1GB is plenty for simple browsing and messaging. Until recently I only used 500MB a month for basic use. The danger is when you start streaming from YouTube or any music services. I recently went to unlimited data (3 network) and have used 6GB in 3 weeks lol

Most providers won't allow you to go over your limit. O2 allow you to go over, but you get drastically reduced speeds once you do.

It's not the time that takes away your data, it's the amount you use. If you browse or upload pictures often then it will take away data faster.twitter shouldn't affect much. Try using Wi-Fi whenever you can.always check with provider to see how much data you've used.