For ever and ever – is a very long time! Only God knows how long the Universe will last – but it seems to have been going for about 13.73 ± 0.12 billion years! (according to Hinshaw et al). So I think God has already had a long time to get used to the idea of eternity.
We have enough problems being patient for 35 minutes (as my friend Jerry discovered when the street (sorry, lane) was blocked by a certain lager lorry!). When we think about God’s timescale, and the scale of the Universe, it helps to get our worries about time and scale into perspective!