I have a couple ideas on how I would achieve this. Not sure how I would script it.
Method 1: (probably the better choice)
Create a loop that pings a server u
This command should wait until it can contact google or it has tried 50 times:
for i in {1..50}; do ping -c1 www.google.com &> /dev/null && break; done
The for i in {1..50} loops 50 times or until a break is executed. The ping -c1 www.google.com sends 1 ping packet to google, and &> /dev/null redirects all the output to null, so nothing is outputed. && break executes break only if the previous command finished successfully, so the loop will end when ping is successful.