How I got my babies ready was weaned at 7months(i prefer the later wenaing id=f mum is up for it) Then I do basic ground work and respect etc until 1 and a half at this point I have gone on walks and can do everything on the ground with them I take them in the box to local shows and walk them in hand for an hour to expose them to stuff I then turn away untill there 3 bring them back in and begin breaking them after six months I generally turn away again to allow them to mature physically and mentally. Then bring them back in very slowly with mainly hacking and light schooling sessions for half an hour or so daily I don't do any jump related activites until I can control my horses speed and tempo and there balanced. I generally introduce jumping by free schooling for the first few weeks so they can figure out there feet etc before me on there back it takes me a year year and a half to school over baby courses so when there 5 and a half im jumping about 70-80cm. I like to build there confidence super super slowly(dont ever listen to people who start the sentence with lets see how high he can go).
With carefully foundations in place you can then work through the levels my 9 rising 10 year old is flying through them due to careful consideration of her confidence, ability and joints.
Also I very very rarely jump at home for instance I stopped competing in sept and wont start again till march so I wont be jumping her at all in this time. When it is competition time and im jumping her once a weeek I rarely home school her jumping unless I notice something I need to work on I spend weeks and weeks on flatwork and road hacking
To give a horse your heart guarantees a love that will last forever undamageable