When should I prune my shrubs?

It depends on variety @RoyP. It looks like you have some evergreen euonymous in there and they only get pruned to keep them to shape or size and in mid to late spring.

The photo is too fuzzy to identify the rest but if you know their names, look them up on the RHS website and it will tell you when to prune.

 

Different shrubs need pruning at different times, especially flowering ones, so difficult to say without know what you have.

They dont look out of control to me so do you need to prune them?

 

Don't tell my shrubs that please @pete.

 

As already mentioned it's not wise at all to just blanket prune shrubs. They have different requirements.

Flowering ones in particular because if the flowers develop on the previous years growth and you've gone and lopped it all off, then you ain't getting a display!

Keep your tags when you buy them. Also research on line, and of course seek advice on here too.

 

I've never pruned shrubs according to requirements. Having taken on a new garden a year ago that was untended for a year beforehand, I'm now having to tackle all of them as they are overgrown. If that delays them flowering for a year, it's not a problem for me. Some may think there are guidelines/rules to follow but all plants are forgiving and I've not had one die yet. In fact many of them have bloomed fully this year after quite a harsh pruning.

 

As above, there is no one hard and fast rule for pruning shrubs. Variety and flowering times dictate for best results.
Many plants can be rejuvenated by hard pruning at the wrong time of the year but some, like magnolias, will sulk for several years. Others may even die. If you are happy to take a chance, go for it when you feel like it.

 

All those shrubs look healthy and tidy to me. I wouldn't prune any of them at the moment. You could maybe add an organic mulch to the soil surface either now or in the spring to give them a boost.

 

Agree, they all look pretty small and young, let them live a little first!

 

None of those look like they need pruning @RoyP , so is there a reason why you feel that they do?
If you do some close ups of each type, you'll get help with future pruning, but the back ones certainly look like Euonymous fortuneii which can be trimmed at any time really, without much harm.
The general rule is prune after flowering, if needed, so you'd need to ID which ones flower and when. Pruning at the wrong time can mean no flowers, as already mentioned by @Esoxlucius, but it doesn't necessarily mean the end of the shrub if it's done at 'the wrong time'. There's a lilac at the edge of a garden round the corner from me. It never flowers because they chop it back every year, and are therefore removing the old wood that it flowers on.

Rejuvenating shrubs is a different matter, as said by others, but none of those look like they require that yet.

 

I always thought the general rule was, if it flowers before June you prune after flowering, if it flowers after june you winter prune.

But obviously there will be a few exceptions as always.

 

The Japanese say "flowers are ephemeral, so prune for structure first". That said I agree with others none of your plants look out of control.

 

Yes - the pruning of flowering shrubs largely depends on when they flower @pete, and any later ones can be pruned afterwards if, and only if, the timing is suitable - ie not freezing conditions etc. Best left if that's the case, and done in late winter/early spring, but it always depends on the plant itself. Hydrangeas, for example, are largely done in late winter/spring as many people like leaving the flower heads on through autumn, and they can help a little with protection of new flower buds.
That timing, and the amount of pruning depends on the type of shrub, whether it's general tidying or rejuvenating, and the general location and climate, so it's too big a subject to generalise.
Hopefully, @RoyP can come back with more info, and we can give better advice with future pruning.