You can get some general ideas here, but your accountant should advise you on tax issues.
I don't think it matters if you pay yourself €50k in one lump sum or over 12 months. There might be a small PRSI advantage in paying it monthly, but I am not sure. (Certainly there will not be a difference of €11k as you suggest).
If you pay yourself €50k on 1 January , you would pay a lot of tax, but you would get it all back by the end of the year.
I am concerned by the following:
"If I will have 50k on my LTD account"
The amount of money you have in your bank account should not be the determining factor. As a general rule, a one person company should pay and accrue enough salary by the year end to wipe out any taxable profits.
Brendan