You could have 'em now, and they will still be effective in May.
Latest you should wait is 10 days prior to travel, gives the antibodies time to form.
PS it's usually routine to give typhoid for Turkey, but opinions vary.
Most important advice is watch what your eating- no ice in the drinks, sealled bottled water, avoid handled uncooked fruit&veg, peel your own fruit, (cherries on the beach are a no no), piping hot cooked food etc.
You shouldn't have to pay for them if you visit your GP (usually), although this varies from practice to practice. Remember your hep a booster in 6 months.
If you require malaria drugs, (not usual for Turkey), you will have to pay the pharmacist.