Older. The fact that he is clean at the beginning of April and showing a touch of colour on the antlers, suggests that it’s been a few weeks since he has been clean of velvet and well past the colourless stage;
Length of front tines relative to the rest of the antler length is a trait which increases relatively with age;
Sloping coronets with a clear gap between these, coupled with possibly one antler possibly appearing to be slightly advanced compared to the other when viewed from the side or above (‘marching head’)? This is an older beast trait, it would require a more careful look from said angles;
A look at the teeth, both the lower incisors and the molar wear can usually indicate age (to compare with others from your immediate area, so over time your perception of tooth wear (irrespective of sex) and will come with experience, also the relative ‘wear’ and relative roughness eg around the eye sockets, where the jaw muscles attach to the lower jaw, the central skull suture ( which develops more elaboration over time) will also help when visible if the trophy is retained and the skull is boiled - the meat on an older head being also tougher and requiring slightly more boiling time than a younger head will all serve to indicate relative age of animal;
The winter coat is held on to for longer among older animals when compared to younger brethren, the younger beast being first to show patches of summer coat in springtime, the pic suggests he’s still very much in winter coat; the colour around the eyes and lower jaw in the pic also suggest to me that he is older rather than middle aged.
I’d put him in the 5-7 year category personally, you can be pretty sure his eventual replacement will be a bold but cautious 3 year old, which will take a couple of seasons in the territory of ‘old Fred’ to become the new ‘Old Fred’, the first season he’ll be looking over his shoulder for the grumpy old guy who used to live there where he himself has decided to move in, but in the second and any successive years he will be far more intimately familiar with the territory and as a result wise to the whereabouts of the tasty bits from harvest time in which serve as the foundational nutrition which begin the subsequent development of the next head once the velvet begins its journey skywards.
Nice first buck to take, I’m sure you’ll have been just as excited as I was myself back in May 1983 as I yet recall, albeit having begun with stalking the does the previous winter. I hope you enjoy the time spent observing and learning about the lovely roe deer and its ways as much as the rest of us, and permit them a look at life for a duration you yourself might desire, were the hunter to become the hunted - this one fits that category well, so congratulations.